Originally Posted by bluestyle55

*UPDATED 2/23/2010 w/ Updated Video footage (10 min total )*
OK guys….here it is. I have been collecting footage over the past few months. You will find below all the sound readings that should quantify that adding HFC’s onto an Invidia Gemini CBE does not tip the scales on db levels. I am SOOO glad I made the purchase. The butt dyno felt major gains with the adding the HFC to the already existing CBE and CAI setup. Not to mention…the HFC’s will add a slightly raw sound to your setup that will put a huge smile on your face when you hear it driving away.

I am one of those guys who spend a lot of time watching, and re-watching the exhaust videos and contemplating weather a CBE and HFC setup would be too loud. I would like to stress…I have a fairly low tolerance to loud exhaust noise. I believe the Invidia Gemini and ERZ combo is a perfect setup. It is ONLY loud at WOT. Daily cruising readout show only 70-80 db average.
Also…a special thx to ERZ for their unbeatable price and great customer service.

So here are the results…

Stock DB – I do not have stock WOT or 80mhp cruising read outs (if someone wants to give it to me that would be great)

Invidia Gemini and Stillen CAI (A weight)
0-100mph (WOT) – 85 db
Launch (outside car) – 90db
80mph Cruising – 77-82 db
Day to Day Driving - 70-80 db

Invidia Gemini, Stillen CAI, ERZ HFC’s (A weight)
0-100mph (WOT) – 87 db
Launch (outside car) - 93
80mph Cruising – 78-82 db
Day to Day Driving – 70-80 db

Some other interesting facts….
-Invidia Gemini and ERZ combo has NO HISS. I believe all other documented combos have hiss.
-Invidia Gemini and ERZ combo has only a small amount of RASP (typical with HFC add on) To be honest with you I think the RASP sounds kinda cool…gives it a more aggressive sound IMO
-Between the CBE or the HFC’s – the butt dyno says HFC’s you feel way more gain. I still cannot believe that after I have the CBE and CAI installed that the HFC’s felt so much gain. High RPM shifts pull so much harder.
-Check out spearfish25's thread …. also a good ERZ review