Sorry for the late reply. I actually didn't notice much increase in cabin noise with FI RHFC. Just a little bit. Less than 10% increase. It was something I worried about but it was minuscule enough to ignore.

I'm repeating myself, but I thought the biggest difference was how each note of the exhaust seemed more pronounced and free flowing; less muffled. More rumble/gurgle under 3K and you'll make more popping noises. You'll kind of get that gurgle at 2k too.

Xmas list will be RHFC.

U gave me the answer I wanted to hear regarding sound/noise level and increase. Already sexy. But I didn't want a lot more noise. :ughdance:

I ended up ordering the Z1 HFC to pair with my Invidia Gemini. The HFCs just came in today!

How do you like that setup? I've got the Invidia Gemini and am currently on the fence about z1 HFCs