
Originally Posted by
turbomirage
How much psi are you planning on running? You can go with 3" if you would like, but it is not necessary. For your set-up, 2.5" would probably be more than enough for what air that 18G can flow. As stated before, 450whp was put down using a 2.5" exhaust. 4" is ridiculous for an 18G turbo, do not do that. The pain of making it and the $$$ spent doing it will be a waste, when you can make the same power from a 2.5" exhaust. Again though it is up to you... but I believe 3" is not needed and 2.5" would be a better choice for overall performance for your 18G and engine.