Frustrated with axle back
Joined: Dec 2011
Posts: 32
From: NC
Just installed the FRPP KR500S axle-backs on my 08 Bullitt and all I can say is WOW! Well, there are a few other things I can say too. They are louder than stock at idle but throatier and deeper. After 2500RPM they get really fun. And - NO DRONE. I've had Corsa Extreme (no drone), Roush Extreme cat-backs (obnoxious popping on decel and terrible drone at 2K), and stock Bullitt mufflers (nice sound just not enough of it). I've finally found the exhaust note and level I've been seeking. My search for the 'ideal' exhaust is over. Even the mechanic that put them on was 'wowed'...and he is the same guy that switched me between the other exhausts listed above - he didn't have anything to say about them. When he cranked my car up with the KRs I was in the waiting area hoping that was my car I was hearing...
2nd Gear Member
Joined: Nov 2007
Posts: 479
From: Pittsburgh. Pa.
i have 1 3/4" kooks LT and 3" off road h pipe and '08 bullitt axlebacks. sounds good with throttle up. goes good with the whine of the whipple. i would like to hear it from outside the car someday. i got any volunteers to drive?
Thread Starter
Joined: Oct 2009
Posts: 44
From: PA
Can anyone give me a link or a part number for the GT500 axle back? I've read a lot about them but can't seem to figure out if there a FRPP or a take off
is this the same gt 500 axle back?
I have a set of JBA GT500 axlebacks. I'll give you a rockin deal on them if your interested.
Super Moderator
Joined: May 2006
Posts: 8,886
From: Michigan again!
Exley - if you are asking about the stock GT500 axle back then for model years up to 2010 the part number is
The same as the part number for the stock GT mufflers for the automatic GT Mustang.
The GT500 used a lot of stuff right from the Ford parts bin, same things as found on other models. In 2010 the GT500 got a different muffler from the GT.
The same as the part number for the stock GT mufflers for the automatic GT Mustang.
The GT500 used a lot of stuff right from the Ford parts bin, same things as found on other models. In 2010 the GT500 got a different muffler from the GT.
3rd Gear Member
Joined: Mar 2011
Posts: 718
From: IL
Exley, I've got the Pype Bombs. With a stock midpipe, I think they sound fantastic. I wouldn't mind it a bit louder, but then again I'm only 18 
That being said, I've heard of some complaining of drone with these. I don't hear it, but again, I'm young. I enjoy hearing my exhaust as there's a reason I put it on in the first place. I do see how these would supposedly drone less, as they're straight through instead of chambered. However, I think Stingers are straight through as well and are supposedly known for drone.
It's all different to each person.
That being said, I've heard of some complaining of drone with these. I don't hear it, but again, I'm young. I enjoy hearing my exhaust as there's a reason I put it on in the first place. I do see how these would supposedly drone less, as they're straight through instead of chambered. However, I think Stingers are straight through as well and are supposedly known for drone.
It's all different to each person.
5th Gear Member
Joined: Nov 2006
Posts: 2,935
From: Alabama
Exley - if you are asking about the stock GT500 axle back then for model years up to 2010 the part number is
The same as the part number for the stock GT mufflers for the automatic GT Mustang.
The GT500 used a lot of stuff right from the Ford parts bin, same things as found on other models. In 2010 the GT500 got a different muffler from the GT.
The same as the part number for the stock GT mufflers for the automatic GT Mustang.
The GT500 used a lot of stuff right from the Ford parts bin, same things as found on other models. In 2010 the GT500 got a different muffler from the GT.
Joined: Dec 2011
Posts: 32
From: NC
Just installed the FRPP KR500S axle-backs on my 08 Bullitt and all I can say is WOW! Well, there are a few other things I can say too. They are louder than stock at idle but throatier and deeper. After 2500RPM they get really fun. And - NO DRONE. I've had Corsa Extreme (no drone), Roush Extreme cat-backs (obnoxious popping on decel and terrible drone at 2K), and stock Bullitt mufflers (nice sound just not enough of it). I've finally found the exhaust note and level I've been seeking. My search for the 'ideal' exhaust is over. Even the mechanic that put them on was 'wowed'...and he is the same guy that switched me between the other exhausts listed above - he didn't have anything to say about them. When he cranked my car up with the KRs I was in the waiting area hoping that was my car I was hearing...
Correction...model is FR500 S