Exhaust Sizes for GTR's

[Demon]

Just a dum question......What is the recommended exhaust sizes for an R33 GTR....I know exhaust sizes range from 80mm (or 3inch) to 95mm (or 3.74 inch). I had a 95mm exhaust and changed it for a brand new stainless 80mm exhaust and now bottom end power is alot better but top end seems lacking....

It probably depends on your cars mods, but in any case would an 80mm exhaust be too small for a GTR???

Just your opinions guys.....

[pentae]

Go the 2.5 inch twin piping from each turbo to a twin 2.5" stainless exhaust at the back.

[akeenan]

i personally wouldnt go any smaller then a 3 inch 3.5 inch but thats just me.

[Cake]

80mm will be ok, depends if you prefer the more bottom end, or miss that top end. in hpi mag ive noticed a lot of the high powered supras and some gtr's have 80mm systems, where as some do have 95mm and even 4inch.

In general, 80mm is not to small for a GT-R, depends, how hard are you planning to mod it?

[Gradenko]

Demon, I find it hard to believe you saw any difference in the low end with a smaller exhaust. We drive turbo cars, so the very best exhaust system we can have is no exhaust (least back pressure). The only possible reason there would be a power loss going bigger is if the factory ecu over fueled when it sensed extra air flow.

Go as big as you can stand hearing.

[Demon]

Thanks for the feedback guys...

Gradenko, the increase in low end power was probably due to changing my standard cat to a hi-flow cat which I forgot to mention earlier......

i.e. I had standard cat and a 95mm exhaust with a centre muffler, I then replaced the cat with the 3inch hi-flo and also replaced the exhaust with a 80mm stainless straight thru....Bottom end is better but top end is worse....Could it be due to the Mines ECU I have installed, is not configured for the extra airflow by the cat and so is just overfueling to protect the engine?