View Full Version : So Which Exhaust To Buy?

18th April 2000, 18:43
Hi Everyone!
As a newbie to this board and having just ditched my 328ci BMW for an sti6(with no regrets!) Ive just about run in the engine as per instructions and am now looking for some upgrades. Does anyone have anything to say re GGR exhaust system vs ScoobySports? or are there even some more superior exhaust systems available? dont care what it sounds like just whats best for the car..and can someone also recommend a good air filter replacement?

18th April 2000, 19:12
have you a budget to work to?

18th April 2000, 19:18
Not really, but say 1000 ish if that makes sense!

[This message has been edited by Riksti6 (edited 18 April 2000).]

18th April 2000, 20:52
Is that a grand for the exhaust?

OK, I am going to be really dull here.

Having lived with an STi V for just over a year (it has the same ECU as the VI) adding an exhaust/induction/filter CAN (not necessarily will) cause the engine to run lean. This CAN exacerbate the problems of using 97RON as opposed to 100RON.

For a 1000 the very best first upgrade for an STI VI would be a Possum Link ECU - this will increase your torque and enable you to run very safely (and powerfully) on UK 97RON fuel. (Cost 700-900 installed and mapped)

If you are concerned about your warranty - I would suspect that all 'grey' warranties will be invalidated by any after market tuning.

OK - sermon over


Most popular - Scoobysport - backbox, decat mid-pipe, decat downpipe

Most desirable - full BPM stainless handcrafted system - see website to ogle over downpipe

Most noisy in car - Blitz - with, or without the baffles in

Most cavernous - HKS Hiper - 6in tailpipe, good back box and midsection - crap downpipe

All of the above exhausts are good - and I am sure there are others - but these ones are popular.


Most like a mushroom - HKS Induction Kit - unfairly castigated - can be good, needs to be installed 'firmly'

Most like a colander - Blitz - high flow, questionable filtration (like HKS), popular

Most expensive - MRT/Scoobymania Group A Rampod - straight of a rally car - supposedly superb, but expensive

Most flat - use a Scoobysport flat filter (and if you can be arsed, remove the resonator from the inner wing - 45min job - to free up an extra 3bhp) - probably gives best filtration and has least noise


PS I have HKS Hiper and HKS Induction http://bbs.22b.com/ubb/biggrin.gif

18th April 2000, 20:57
HKS Hiper tailpipe diameter is 120mm which, to my knowledge is much less than 6 inches (thank God).

This and all other large diameter (3 inch) almost straight running (rather than million of bends and curves) exhausts will only give their absolute best (and sound less rough and loud by a noticeable margin) if used in conjunction an efficient induction kit, optimised ecu and, if not worried about the MOT and similar issues, beneficial downpipe (not many beneficial ones available).

If the above conditions are not provided, all you will get is more noise and a few hundred rpm higher pick-up point. Upper mid and high revs will always benefit.


19th April 2000, 07:11
Steve McCulloch (posts as Sti5Brigade) is a good source of info on this - he has just spent c1k on a straight through exhaust - sounds the dogs danglies and goes!

Induction kit - I have a Pipercross fitted which was recommended to me by a Group N Impreza preparer - TAS. Can be a bit noisy, but does perform very well, and (according to TAS) is the best commercially available one, and a level above the K&N/Blitz etc - hence why they use it on their Group Ns!

19th April 2000, 11:56
I have a full Scorpion exhaust and a K&N induction kit which cost a TOTAL of 450 and gives some of the best increases seen on any Scoob (see http://dyno.scoobynet.co.uk/uk/stef_reader.htm )
Mine's a UK car, but should work on yours OK. The sound is one of the best, and you've then got 550 left too!! http://bbs.22b.com/ubb/biggrin.gif


19th April 2000, 17:58

you are correct as ever - but keep it quiet - I told my girlfriend that 12cm feels just like 6in!

Even at 12cm, it is still the most cavernous! Although the centre pipes are 3in, the inside of the baffle looks suspiciously smaller http://bbs.22b.com/ubb/frown.gif

Goes well tho' better with good remap http://bbs.22b.com/ubb/biggrin.gif


19th April 2000, 18:24
Oi Gary!

Hmmm.. Full twin dump does make rather a large sound - I love it
Its got a superflow cat at the moment - but I will be looking at this shortly (within 2 weeks) to see if I can get a straight through pipe (and sod the MOT - if the car lasts to that point - depends, in part on my ability (or lack of it) to negotiate car park junctions, ala Paul Frank!)

I really dont think theres a lot in the various systems - they'll all give a bit more bottom end poke (e.g low down torque)- with some bhp gain

One thing about the bpm system is that the rear pipe rusts! - or rather it has a rust surface that needs constantly cleaning! - so much for it being stainless - must be some cheap stuff in there.

Mongoose is cheap on a budget - circa 500 fitted for full system.

Air filters - again not much in it - of all the people I have spoken to Blitz comes off best - it aint cheap though at 170 (yep... 170 for an.... air filter!)

Rannoch is right about going forward. I you want more poke on a budget of say 1000 - do not bother with exhaust and filter as you may have det problems - get in touch with Bob Rawle, and get a mapped Possum with no det, a fair bit more poke - and a big grin!

Then look at Exhaust and filter - then a bigger turbo, etc, etc

20th April 2000, 10:38
We have restructured pricing and soon the Europe launch [3 months] will have more inventory than you could imagine.

The exhaust we have standardised on are the full HPC [ceramic] coat the whole way through. This makes us the only company to have this in the inventory. We believe the price introduced will shake the Subaru world which is why the "quite" period.

If anyone has any immediate interests some stock is available albiet trickling...

By July all will be apparent....

Hope to get this right since stock problems did plague us into the UK...

Oh by the way the BPM 2.2 litre stroker is available with 4 weeks...

Stay tuned

Greg www.bpmsport.com (http://www.bpmsport.com)

20th April 2000, 17:59
Think mine is called L series?
Does full hpc coat mean that its supposed to be rust proof - downpipe looks like it did the day it was purchased (a couple of months ago) Centre section is rusting all over like a standard exhaust system - it certainly aint HPC coated.

Back section is ok, except for exit pipe which has a rust surface and constantly needs cleaning.

If it is hpc coated then that means to me on my sytem that its inferior, to the always new look of a stainless system.

Notwithstanding this it sounds awesome

20th April 2000, 21:50
Hey Brigade... http://bbs.22b.com/ubb/smile.gif

HPC is a ceramic based coating... that should prevent water penetration... it is baked onto the pipes at about 500 degrees... but if the preperation isnt perfect then it can come off....Or rust through.

Why not HPC stainless .... best of both worlds... lol

*please dont start getting into the various metalurgy aspects of steel to stainless*


21st April 2000, 01:38
The L Series will no longer be in the series since all items will be stainless with HPC coat.Usually the downpipe was the only item coated. This has changed in two months from now.

The UK is exceedingly salty and the systems have to be made to correct specificaton.

Thanks for your patience..


Mark Pitchford
28th April 2000, 13:50

How is the mongoose?

Did you get my mail??

29th April 2000, 20:36
I haven't got a Mongoose!!!! http://bbs.22b.com/ubb/confused.gif

The 22B that was at the recent Scoob/Cossie shoot-out had a recently fitted full BPM exhaust system, which was already rusting on the tail-pipe and silencer.
It was fitted last week by C&K in Manchester I think.
What's the story with these systems and rust?
Is this normal, as it's the second BPM I've seen, and both went rusty immediately.


2nd May 2000, 07:37

As mentioened the units we had shipped to the UK were in mild steel with no HPC coating for the rear and mid sections.The downpipe were HPC coated and will continue to look good.

If you follow the earlier response in this thread, we have standardised on HPC coating across the board since the UK is very salty..

Thanks for continually "assessing" the rust , it helps keeps us on our toes.

Greg www.bpmsorts.com (http://www.bpmsorts.com)

2nd May 2000, 10:29

Are you going to do the decent thing and offer a cheap upgrade to UK customers that were sold your quick-rusting mild steel kit?

I would certainly want my money back or a higher quality replacement if I bought such an expensive exhaust system and it started rusting within weeks! http://bbs.22b.com/ubb/eek.gif

By all accounts, you can't have sold that many mild steel systems over here so far, so this shouldn't be to catastrophic in terms of number of replacements.


2nd May 2000, 12:32

I'm looking into getting a new exhaust, did you get my email asking for more details?

i sent it to: bpm@bpmsports.com


greg dot hilton@compaq.com

2nd May 2000, 23:31

In answer to your question , we will indeed be offering the upgrade option.

The upgrade cost will be negligble when taken into account the units will be full HPC coated.

It will be [with our research anyway] the first company to offer full ceramic exhausts as the base line option..

Greg www.bpmsports.com (http://www.bpmsports.com)

3rd May 2000, 07:18
Any comments on the BPM exhausts from anyone with one?


4th May 2000, 02:43
In Australia the BPM system is the leading systems, and had performed extremly well in exhaust test and dyno shootouts.
Added to that the exceptional quality of the workmanship of products like the Twin Dump and the new Twister muffler is AWESOME!! Made huge improvements to my WRX. Very recommended

[This message has been edited by Nige (edited 04 May 2000).]

Bob Rawle
4th May 2000, 09:49
Having seen examples of the BPM system I would not say the quality is excellent, more like satisfactory. The items I have looked at have all the usual defects such as porous welds etc but then so do most.

The HPC coating looks nice, this can be had in the UK as well, anyone buying any exhaust system (in any material) can have it HPC coated. I would be interested to know from Greg which type it is ... some keep heat in and some prevent heat absorbtion. As to performance any good system will provide extra, the trick is at what area of the rev range, I have mapped a Link on a version V with a full type L BPM system, seemed to work well, system quality not that good (see comments from STibrigade above). The downpipe design looks good, wether it works or not we will soon find out.

The Scoobysport downpipe with HPC coating looks and works well on an STi V when coupled to a 3" system at any rate.

If anyone decides to have the coating done then its easiest (and cheapest) to have it put on before its been on the car.


4th May 2000, 10:43

I guess there is an obvious lag in our systems that you have seen in the UK and the ones we are currently manufacturing.

Suffice to say we have taken whatever feedback that has been presented and we have now what we consider to be a "superior" product. The UK has been a good platform due to the high salt content, which has in turn let our tweak our design to meet all specifications.

The remainder of the exhaust now matches the quality of the downpipe , so I guess it will soon be time to show the new systems.

Our new downpipe has no welds ie it is a full mandrel bend design and is one piece. So we would like to show continual evolution in product. We feel when we relaunch , BPM will bring some competition and offer something to the UK that the end user will benefit from.

As to your HPC question , please see our webpage which explains why we use this coating.

We have done research on many coatings out there and HPC is what we believe to be the standard most coating companies strive for but few reach.

Greg www.bpmsports.com (http://www.bpmsports.com)

[This message has been edited by BPM (edited 04 May 2000).]

5th May 2000, 11:48
There has been some serious dyno work with different systems and it was clearly found that the best system for power was a 4" dump pipe splitting to two 3" pipes running to the rear, This is very loud but has a 28kw advantage over the next best 3" system. This big difference makes it easy to justify the big stereo http://bbs.22b.com/ubb/smile.gif This jump was tested on a car with some considerable modifications but still not too far outside the realms of what you guys in the U.K. are heading towards.

9th May 2000, 12:07

What did that do for mid-range torque? The received wisdom here is that above 3" (on an STi) you may get a better top end but you lose some engine flexibility. I still haven't heard a fully convincing technical explanation for this, but that doesn't mean it isn't true. Any hard facts very gratefully received.

-= mike =-

19th May 2000, 14:38

As far as I recall, torque and mid range losses occur when there is too little back pressure, as can happen with bigger bore pipes.

Don't know exactly why, but believe its pressure related.

Anyone out there able to answer the question?

19th May 2000, 18:48

please, for God's sake, not again about the front and back pressures! We had this once already on the ScoobyNet and it never clarified anything.

Just make the damn exhausts work and leave the pressures alone. If that is all that help your cars to work well, you have a much bigger problem.

all the best

20th May 2000, 01:42
O.K here it is as I understand it, No backpressure on a turbo car is best, The turbo provides all the backpressure that you need. one of the best allround performing exhausts is the Apexi N1 it is a very straight design even around the rear diff, It has a five inch tip that you can put a silencer in, this is like a 5" can with a 2" hole on the center with baffling filling up the remaining space, this makes the system quiet for the street and when you get to the track you remove baffle and then you have the best of both worlds. In AUS not many people have just a backbox, they change the whole system, nearly all systems are Stainless steel and the average cost for a full system is about $1500AUD

20th May 2000, 06:43

But have any of the N1 systems that you've seen been legal ? ie. cat converter.
I've seen and heard a N1 system and it is bloody loud but sounds unbelievable. But the owner didn't have a cat in it.
I ordered the RS system at the same time and had a cat put in afterwards, still sounds very good, quiet at idle but a nice note when I bury the right foot.

21st May 2000, 07:59
The N1 starts at the bottom of the downpipe, If you are going to do track days as I do then I put the cat in between the downpipe and the N1, This is bolted in on both sides, I have a straight through section that I replace the cat with at the track, If you want the best street setup then have the cat put in the downpipe.