Fast_Blue_Scooby

I have a MY99 UK Turbo, I already have a Scoobysport backbox and ITG air filter fitted to the car and was thinking about whether to replace the centre section and the downpipe. However I have a few questions that I would be grateful if anyone could answer:

- What improvements should I see if I just replace the centre section, ie remove the second cat? Also will the car still pass the MOT with just the one cat present in the downpipe?

- What extra benefits will there be if I replace the downpipe as well? Also I take it that the car will fail the MOT with both cats replaced? Or has anyone got their car through an MOT with no cats on a UK Turbo?

- Will I need to upgrade anything else on the car, eg ECU to fully take advantage of these mods or is that not needed?

- What about replacing the up pipe at the same time, or should I not bother?

Thanks in advance...

Chris L

Biggest improvement in terms of performance and BHP will be to remove the downpipe - this is the most restrictive part of the exhaust system on an MY99. Replacing just the centre and leaving the standard downpipe will only produce marginal gains, as the biggest cat is in the downpipe.

Because the main cat is in the downpipe, then passing an MOT shouldn't be a problem - if you leave it in place. I have heard of people passing MOTs with just the center cat in place - although this cat is much smaller and you would normally need to make sure that this is thoroughly warmed up before you take the car in and ask that the emissions test is done first.

To be honest, I'd decat the whole thing (I did on my old MY00 - ran it for more than 30K miles with no problems - sounds great - especially on the overrun, goes well ) and fit an ITG panel filter at the same time.

Decatting the whole exhaust should see something in the region of 25 bhp - it is certainly noticable. When it comes to the MOT - I would suggest speaking to one of the the independent suppliers who advertise on this board, as many will supply and fit a temporary catted centre section that will pass the MOT emissions test.

No need to change the turbo up pipe as this only applies to the new shape WRXs that have a third cat fitted to meet the tighter emissions standards.

Chris

Edited to say I see you've already got the ITG fitted
Also might want to consider fitting a boost gauge, just to check what boost you are pulling - this will increase with a fully decatted card. You won't need to replace the ECU, as the car will adjust itself over time. You could do a manual reset of the ECU if you don't want to wait.

Chris

[Edited by Chris L - 12/28/2002 10:23:13 AM]