View Full Version : Changing mid-section but not downpipe...

21st May 2000, 01:15
... Does it make sense? Improve performance / sound?

I understand that most people change the backbox and downpipe first, and only then change the mid-section.

What about doing it the other way around? My reasons are:

1. Unlike changing the downpipe, the mid-section will not invalidate the warranty (apparently)
2. Will pass MOT without the mid-section's cat; won't without dp
3. Cost: 40 for mid-sec vs 300 for dp

Does it make sense and should I bother?

Many thanks for letting me know.


21st May 2000, 08:21
Dealer will be more sympathetic with Mid-section replacement - Prodrive remove rear cat as part of PPP

Car will still pass MOT with just front cat - see above!

Cost is more 70 vs 200, but still cheaper, though performance gains not as great.

Makes sense and worth doing - performance gains are noticable with straight through pipe, but get non-silenced pipe for full benefit, most manufacturers have stopped making non-silenced ones! Scorpion still do one - 69 from Motech, or Scoobysport do one for c120-130?

I have Scorpion one fitted http://bbs.22b.com/ubb/biggrin.gif

Ian Cook
21st May 2000, 08:59
I have a Scoobysport centre section, unsilenced cost 45 quid plus VAT ? It does make a difference, although not as much as the DP to performance, a little louder, but again not much (inside http://bbs.22b.com/ubb/wink.gif ). I had the car checked for emissions after replacing the cat, as an experiment, and the readings never changed from before to after so it will definitely pass MOT and roadside inspection.

21st May 2000, 11:40
So, Ian, would you recommend doing it? Or will my money be better spent elsewhere (boost gauge, breaks, etc)?

Ian Cook
21st May 2000, 12:59
Difficult to say if its worth it, i think so, but then what do i know http://bbs.22b.com/ubb/wink.gif LOL

22nd May 2000, 09:09
The Scoobysport is not a replacement pipe per se, they cut out the cat and weld a piece of pipe in its place. Bear this in mind as once done, you cant go back http://bbs.22b.com/ubb/icons/icon4.gif .

Makes the car louder and seems to improve pick up a bit.

Cost was 50 quid... worth it in my opinion http://bbs.22b.com/ubb/cool.gif.

22nd May 2000, 10:01

I think you'll find most people change the backbox and centre-section first, and then possibly the d/p as it's cheaper and simpler this way.
Gains are probably slightly higher with a d/p change, but I wouldn't have thought by much.


22nd May 2000, 16:42

I thought it was the other way around - mid-section last, and big gains from changing the d/p (because it's a big cat nearer the engine - so more restriction)?

Is this how YOU did it or did you change the whole exhaust system in one go?

So would you recommend changing just the mid-section then (I've already got the backbox)?



23rd May 2000, 17:22

I changed the back/mid sections first as it was the way the Scorpion system came, ie, cat-back, so included the de-catted centre pipe.
If you already have a back-box, then perhaps a d/p change is better.
I wouldn't have thought there'd be much difference, although it is argued that removing the front cat will give slightly higher gains.
Not much in it though.


23rd May 2000, 17:26
Just out of interest, I tested emissions on a Link equipped car with no cats at all. High idle gave CO of 0.12% and unburnt hydrocarbons at about 80ppm.... IIRC the limits are 0.4 percent CO and 200 ppm on hydrocarbons... hmmm.... need to double-check....



10th June 2000, 20:43
Stef, u alone aint "most people"...i changed, in order

1) Dp
2) BB
3 Centre

So, up yers!