New GReddy kit installed and tuned got me to 264/218 @9psi with stock everything else. Was told that was about as good as it gets with the stock exhaust. Question: looks like a Berk HFC is a relatively inexpensive improvement in flow, but is it a waste if the rest of goods stay the same? I would also take the time to get a new 4 bar MAP, bump psi to 10, and retune. Am I dreaming?

 

If you want to keep it quiet and emissions compliant, get a cutout.

Best of both, although this will require a retune.

 

Most people with the Greddy kit have great results with a 70mm cat back with either the stock cat or a HFC...

I ran 7psi, 70mm catback, stock cat, and made 300whp on a dynapack, figure 275whp on a normal dyno

 

The stock cat is very restrictive. A HFC and stock exhaust would be a good middle ground IMO.

 

can you still pass smog with a HFC??

 

Depends on where. CA visual inspection may fail. Other states might not notice. OBDII emissions check won't notice anything as long as your car is running well.

(Berk HFC and Fujitsubo exhaust were my first two mods to improve my Greddy kit.)

 

Get a HFC or better yet a TP it's worth it on the greddy kit with stock exhaust. Probably the best mod for the kit. Don't do a cut out, greddy can't handle it.