So its about $250 for a used VAFC and harness. Everyone know these things are good for lowering VTEC and leaning out the mixture at WOT for best power. So, I will be running the OEM cat because of sound and emissions. My question is, is a VAFC worth it with the OEM cat? How much can I lower VTEC?

 

With stock cat you can't lower Vtec down much. At most around 5400 for engagement. I'd go with an actual engine management and get a real tune.

 

It's not worth it if you're stuck with the OEM cat, but it would certainly be worth it if you switched to a HFC. You should be able to pass emissions anywhere except CAs visual test with a HFC and I've never been able to tell the difference in sound. For less than $500($250 used VAFC + ~$220 HFC) I don't think you'll find anything else that will yield the power this combo will.

 

I like the sound of the OEM cat. I will try a magnaflow HFC. I think that is the one berk uses.