That should be fine. I run the Stillen intake with my Z tube (got it off a Z owner for $20) and Crawford plenum and did not experience any noticable loss in low end torque (had the intake before either other piece). The Z tube is a good mod in and of itself, though; nets about 6 RWHP. Don't forget you need to extend it to fit the FX; the best way is to get a hold of the short dlexible piece from a stock G35 intake and have a muffler shop make a small coupler out of stainless or aluminized tubing.