Agree 100%.

The difference in emissions between stock cat and hfc is minor (except when cold), whereas emissions difference between cat (stock or hfc) and tp is huuuuge.

Its highly irresponsible to run a tp when a few bucks more makes such a dramatic difference in emissions, and has minor impact on power level.

 

My car's previous owner's sole mod was a CARB compliant K&N intake and he scratched the crap out of the OEM airbox cover so I kept my K&N on. When I was going back and forth with Gernby during tunes, he did note that there was additional airflow over the stock airbox so he had to correct some parameters to account for that, so I'm unsure how to process the restrictiveness of the K&N versus the OEM airbox.

I don't believe the K&N intake is more restrictive (air flow considered alone) than the OEM airbox, but with heat soak and under hood temps considered the OEM airbox will be better overall in most conditions. I think both the K&N intake and the OEM airbox would both benefit from a dedicated airguide/snorkel.

 

Diy 3.5 intake with a velocity stack and aem dry filter. I did 232/165 on a mustang dyno.

A local who has a password jdm intake was only able to manage 222.

Were both basic bolt on intake header 70mm hf cat and exhaust.

After i went from kn intake to the 3.5 intake i was lean by 0.5 on afr from 4.5k to 8600

Also as a result i needed less timing to make more power indicating much more flow