My thoughts on EPA...
I had to take my 32 there last year for heaps of reasons..... They're not stupid and will spot all of the following:
ANY sort of boost controller - trust me I spent ages hiding mine and he spoted it in 2 minutes
Any sort of oiled filters are ILLEGAL
Only allowed 1 inlet modification, filter or cooler or inlet plenum etc etc... but not more than one
Removable silencers are passable if the securing bolt is welded in
ANY sort of air/fuel or timing controllers are illegal, and they frequently remove the kick panel to check ECU and wiring associated with it.
When I went over and passed, I had FMIC, non-oiled pod Filter, 300ZX AFM, custom chip in my ecu, welded in silencer (89.8 db with silencer!!!), and a high flowed VG30 turbo.... the only thing they picked was two inlet mods but let it passed anyway. My chip passed emmisions test with flying colours... they even commented that it was way below the maximum allowed and heaps less than most other skylines....
Good Luck with your test...
Doc.