2.5inch vs 3inch downpipe

[lucifer666]

Surley though before cats were fitted under law, turbos were run problem free. Or were they more robus t then? And are the barings worn by overspooling and wouldnt a stage2 map have parameters set up so if it spools too much then boost is cut? Cheers for your advice

 

[Mark300zx]

I think it is a change in the pressure on the bearing that's the problem, the back pressure provides some support for the bearing, you remove the back pressure and the bearing floats more laterally so causes a problem, again this is a lot of my supposition and internet gubbings!

 

[Jimmy.D90]

i had the 3" downpipe on my old boc along with the milltek catback, made the exhaust system sound nice plenty more turbo noise, didnt give me any problems at the time but i sold the car 2 months after so didnt really have much time for problems too arise, and the seat dealer that bought the car back off me werent bothered about the extras I put on so im guessing it wont do no harm ?? and with the re-map it was alot faster

 

[lucifer666]

Was that decat? Was it an offtheshelf downpipe?

 

[Jimmy.D90]

Was that decat? Was it an offtheshelf downpipe?

couldnt tell you mate? i dont think it was a de-cat just high flow sports cat, my mate who has got his own tuning company took it for 2 days and brought it back all installed and re-mapped for me but the money i paid it was worth it