From what I can gather from all you guys and girls out there, changing the D/P (to for example a Scoobysport one) seems to give the biggest bhp and torque increase in comparison to the other 2 sections.

Question is, if I don't have the centre or B/B changed from the standard 99T spec UK car, will the increased bhp from the changed D/P be decreased?

Zak

 

The main way that replacement exhaust components achieve their gains is by removing any restriction in the system, thus allowing the gases to exit more easily and reducing back pressure somewhat.

There is restriction in the original system in the front pipe in the form of a cat, a cat in the centre section, and a very large silencer and small diameter channel running through the backbox.

Individually, the front pipe is likely to give the most noticeable gains, compared to the other sections, but you will definately notice the best gains by removing all restriction. Leaving the original centre and B/B will cause a type of bottle neck effect at the backbox, as the diameter of the channel through it is smaller than the rest of the pipework, ie 2.5"

Just do the lot mate

MS

 

Yes but the reason I don't want to do the lot is because I don't want a Prodigy concert banging inside my head whenever I'm driving! Unless it's coming from the stereo!

The reason for the post really was to find out if changing the down pipe will increase bhp or if the standard centre and B/B will cancel out the benefits of fitting it.

Zak

 

I honestly believe, that having now changed the full system, one bit at a time that the D/P gave the biggest single gain, maybe not in outright bhp, but certainly in the way the car runs with the d/p done, smooth is just one word to describe the car afterwards,!
If I were doing it again, the D/P woulb be the first bit I would change.

Ron

 

I only had the SS down pipe fitted on my P1. Everything else stayed the same.

The effects are agreeably noticeable.

Simon

 

I've just done the DP on my MY99 Wagon, and it makes a big difference to low down acceleration. I've got the std center section and a P1 backbox ( same as std one I think other than the tailpipe ) to keep the noise down and I am very pleased with the results, so much so that I'm not going to bother changing the back box.

You can fit it yourself as well, takes about 2 hours....