medders

I'm looking at putting a new or part system on my P1.
Just driven a full Scoobysport decat P1 (thanks Listers) and it sounded wonderful. I also am led to beleive that performance gains of up to 20bhp can be expected from a decat setup.

I know I have to change the downpipe (probably to a scoobysport) and I want to put the Prodrive backbox on for more noise (but not too much)
What benefit would I get if any from a new centre? Does a standard P1 center have a cat in ?

Please help, I'm confused.

Cheers

Medders

john banks

Don't have a P1, but I gather STi5/6 and P1 have a downpipe and a centre cat, but I'm sure someone will correct me...

DP decat gives the biggest gain, followed by the centre section (much less) and then the backbox finishes it off. If you are going to keep a cat, the centre section is probably the one. If you remove the centre cat, you can sometimes pass an MOT by putting the original one back in if you warm the car up well.

Always run on SUL if you decat, and consider OB also. Also may want to consider checking or monitoring air fuel ratio, as decat can make you run lean esp on import or P1. Even more so if you fit an induction kit too.

John. MY00 PPP DP K&N 57i soon Dawes MBC. And it would have made a good impression of chasing P1's unless you start modding them, and then I'd never keep up

Andy Tang

iTrader: (3)

I thought the P1 only had one cat, the downpipe one.

The centre section althought cat less is quite restrictive by all accounts.

Again, I'm sure someone will correct me if I'm wrong.

Andy

john banks

http://www.iwoc.co.uk/modsairflow.html

Sounds like Andy is right. According to this link STi cars up to the middle of MY98 had a centre cat, but since have not, and the P1 does not.

A catted centre would be easy to fit (10 mins) for an MOT and some garages will lend you one.

The magnex centre section with resonator has been a popular option. I am quite happy with my see thru STi bit, which sounds like it is probably similar to the one on your P1. Along with the PPP backbox, the whole thing is fairly quiet. You could always change only the DP initially and see what you think of the noise. The DP will take around two hours to fit. If you do it in stages you will know the improvements in performance and noise levels.

Dennis Hough

My STI5 type R had a downpipe cat and the centre had a resonator or expansion box plus one more .. This may be th etother cat mentioned in the bbd item.
I had a full downpipe , mid without cat and rear box from Scoobysport and ITG panel filter. Boy was it loud but there again i had no sound deadening as standard on my 2 door import... At this point i decided i needed to be a little more quite and took off the rear box. Much better with the STI box back on.
Since then i bought a Power Engineering centre with Sport Cat (£400) and fitted that. Its now more bearable at all speeds with the Scoobysport rear box back on and the Power Eng centre.
At this point i then added the Scoobysport equal length manifold and that was a bit quieter again.
Since then i have fitted some top quality rubber carpet underlay across all the boot floor and under the rear seat base and back, cost only £10. Great result!!!!
I can again hear my Cd's and dont get deafened on motorways going to /from work. The noise outside the car is good and not like it was with the whole Scoobysport exhaust fitted originaly.
Anyone thinking of doing the exhaust mods should always do a test run first. I didnt and suffered the noise!!!