got jap import 1990 T,T, having st,st exhaust made, taking of the cats, coming straight down from the down pipes turbo pipes will be put back on the new exhaust. old pipes were only 2inch die new pipes will be 2.5inch die, will the car have to be re tunned, and will my fuel comsumption be a lot more, they have told me it will de restict my turbos and engine, i have got turbo timers fitted on the car box is underneath the stearing colume. will that protect my turbos. if the spellings bad because im pissed off it keeps raining and i whant to take the roof off.

your car wont need re-tuning and your fuel consumption wont increase just by changing the exhaust.You may notice your turbos will spool up a bit quicker and the exhaust note will be a bit nicer (mine was)now is a good time to upgrade the air filter if it is still standard.If you are talking about the top speed restrictor then the exhaust will not get rid of that, just try driving over 112 mph, it may have been already removed.

Paul

Hi Shaggy,

 

Just thought I'd reply and present my 2p worth

 

First of all, increasing the diameter of the exhaust system pipes will make it more free flowing. As you know, the standard Jap spec exhaust has restrictors build into the end bit of the centre section so as to pass the strict Japanese emmision tests. Once these restrictions have been removed you should experience better response to accelleration and low-medium end "grunt".

 

Second, removing the CATS will cause the so called back pressure in the exhaust system to drop. This back pressure is normally used by the turbo's to control the speed at which they spool up (i.e., spin). A reduction in back pressure will cause the turbo's to spool quiker and more freely, thereby exerting a higher pressure on the rear turbo seals which may lead to blown seals and oil leaks. I would advice you to check the integrity of the turbo seals prior to removing the CATS. If they are in poor condition either get them replaced or leave the CATS in place.

 

Third, a turbo timer is a great invention to cool down your car's turbo's to prevent the cooling oil to bake onto the system and causing it to seize up. Word of wisedom, at the end of every journey you make, take it very easy on the turbo boost. For the last 2~3 miles don't let the boost go past the 0psi mark. This will allow the extremely hot oil in the turbo's to cool down before you turn off the ignition. Turbo timers should allow you extra cooling to make doubly sure you're not breaking your turbo's. They're very expensive to replace!

 

Fourth, you're not the only one who's pissed off at not being able to take the T-tops out! Why I ever moved to the UK is beyond me ... oh yeah, it was love ...

 

Hope the above makes some sense. Good luck with the manufacturing of the stainless steel exhaust!

 

Cheers!

 

Danny

Be ready for a major increase in noise with the cats off and straight thru big bore system. Mines are back on and it is still loud but just OK. BYW according to Stillen the cats off is only worth 5 - 10 bhp I think and as others have mentioned, taking the back pressure off the turbos can finish off the seals on a car with a decent mileage under its belt.

 

Willie