Some of the mods I currently have. The top photo is my warm air intake, made out of 5" dryer duct routed to hover just over the exhaust manifold. Would it be worth it to downsize the duct diameter to increase velocity?
Second photo is part of my Keman intake. Top resonator has been removed and replaced with high heat resistant pvc pipe. Not pictutred is the bottom resonator delete and the cut open air box to allow more air in... the stock intake was sipping air from 2 1" ports
Last is a vacuum leak for timing advance. This mod seems to be special to just the ZX2s... It has been tried and test true by Tygen1 to cause all benefits and no harm. Gained 1-2* of timing and ~1.5 mpg's from this mod alone.