ffk_pennywise

I recently installed Pypes Long tube headers with an o/r H, and Detroit Rocker cams on my 07. I didnt like the way it sounded and it was way too loud. Horrible drone and tons of trumpeting. I decided very quickly to have Pypes high flow cats spliced in to take the edge off and get ride of the exhaust stink that was permeating the cabin. I used a db meter and took before and after readings that I thought were interesting and maybe they will help someone else. Now to be fair, I want to say up front that with the o/r H, the original installer left me with a lot of leaks and a misaligned muffler that may or may not have been causing some of the horrible sounds I was hearing. I dont know that for sure but I'm throwing it out there. Yesterday I picked up my car from a different garage who installed the cats and tightened and adjusted all the different clamps. I was not prepared for how different it made the car sound. Really took the edge off the way it was screaming. No more trumpeting or horrible drone. No more rattles and no more stink. Still has that great cam lope and an evil growl when you get on it. Nice roar at WOT. But when your just putting around it no longer sounds like a Chevy truck. I would have sworn it cut the volume in half, but my sound meter says differently. Here are the not-so-scientific results.

O/R H:
Idle from 5' behind car when warm - 101db
75mph with windows up - 93db
WOT windows up - 95db

Catted H:
Idle from 5' behind car when warm - 101db
75mph with windows up - 90db
WOT windows up - 96db

Basically no change in volume, but without the rasp, trumpeting, and drone, which makes me perceive it as much quieter. I imagine the lack of leaks plays a big part in that as well.

hammeron

any videos of before and after cats? interesting results and i'd love to
have long tubes but my neighbors would revolt.

ffk_pennywise

Videos will be made soonish. No before/after though.

Nuke

Cool. That has me re-considering some of my modding choices.

onederful100

good to see somone with objective exhaust results
i also use a decibel meter to measure exhaust loudness.
its interesting to discover what sounds louder or not as loud, may be different on a db meter.
what some say is louder, in fact may not reflect that on a db meter.
you thought it was more quiet, but in fact it was about the same in loudness.
but it did clean up the sound, so its better.

could you get some db readings from the back when you rev it?

doode

For real ?

Holy crap.

Your neighbors must love you.

D'prived

I recently ordered some Kooks LT's and catted H-pipe. Originally I was going to get the O/R H-pipe but the guy who is going to do the install told me that if I want that muscle car growl then I wouldn't be happy with the O/R pipe PLUS he said it would be way too loud. So I went with the highflow catted H-pipe. I'm getting them installed this weekend so once I get a video I'll post one up.

Acerbus 2.0

I can confirm this. I bought both the catted and o/r xpipe for my Amercian Racing headers, and I noticed no difference in volume when using the catted version from the non-catted. All that changes is the tone. It goes from a clean "WOOOOOHHHH" to a more of a nasty "WRRRRAAAAAHHHH" kind of thing.

FOR SCIENCE!

ffk_pennywise

I'll see what I can do Onederful100.

I think you hit the nail on the head Acerbus 2.0. You also made me laugh. lol.

madcap

Hey there pennywise - good to see someone else on here from STL! Only had my '09 for a few weeks, but starting to look for shops to do cams and LT headers - any good recommendations, and do you mind sharing what the installs cost you in town for those?