Quote:
Originally Posted by ihiryu
Has anyone done the stock Nismo catback with twins? I was wondering what kind of power it would be restricting?
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You'll be giving up spool speed... Could maybe make up
some of that with a boost controller, but you really want to open up the exhaust to keep your turbos moving. Also keep in mind that TT'ing your car can be an exercise in heat management and restricting your exhaust will allow a greater buildup of heat that would otherwise blow out the tailpipes.
Now, depending on your setup there can be two sides to the coin. IIRC, you are going with GTR turbos, no? Do they have internal wastegates? I am running an Invidia Gemini catback, which is relatively small (dual 2.36") compared to what a lot of TT guys are running (dual 3"). Because my kit is internally gated, and the internal gates in my kit are so small..even with my relatively restrictive exhaust I start to get a little boost creep at the top of gears 3+.
If you are doing GTR turbos - are they journal bearing? That may slow the spool as well.. so there are multiple tradeoffs and compromises depending on how your TT setup is configured.
For the guys that are running ball bearing turbos and fat external wastegates - you'll see most of them have dual 3" exhausts for good reason. =) They are maxing out the spool and don't have to worry about creep.
All of that being said, a plain nismo exhaust is going to be more restrictive than you want for pretty much any setup. Upgrade for sure.