Hello guys I have 2003 g35 auto sedan. I have plenum spacer, ztube, k&n drop in (stock air box) , ground kit, getting high flow cats (berk) with stillin cat back, plus I have uprev tune ( from seymor4 ) hes amazing btw. I'm looking into getting 75mm throttle body but I'm reading you need 3.5in intake to really gain from the tb. A few questions I have are do I need really need the 3.5 in intake or is ztube and k&n enough? If i do use 3.5 intake do I need to upgrade maf sensor if I use 3.5in sensor housing or is stock sensor enough?

 

Seymore should be able to handle you, but if a stock maf can handle a Vortech, it can handle a larger intake.

maybe I’m thinking too hard here, but if the TB is only 75mm, the stock Z tube is already 76.3mm, how would there be an improvement?

the plenum is the biggest choke point on the platform. Port / polish on the intake manifold / plenum can make pretty impressive power gains. Not sure if a 75mm TB makes sense for you at this time .

 

Idk if I'm wrong but I read every where the z tube is only 3in not 3.5 and that the maf housing is only 2.8in but that's just what I read I never measured my self