I figured I'd share the latest project I recently completed, especially since the right sound is something that the '07-'09 GT500's just don't have from the factory.
I added FRPP's 5230-S (aka, GT500KR mufflers) a year or so ago. Stock, the car sounded like my grandmother's V6 Buick with some kind of warble. These mufflers were supposed to give the car a "better" tone without adding any kind of drone.
Well, they held up on the drone, but the sound from the tailpipe was a bit on the raspy side. As much as an X-pipe mid exhaust stream might have been placed on these cars for maximum power - the fact is that the sound isn't commensurate with the power. I never liked it and always felt as though my '09 would never sound as good as my "done up" '90 coupe.
I had noted with interest the fact that Shelby had cut out the "X" and replaced it with a genuine "H" section. All the magazines that reviewed the '08-'09 KR's made positive comments on the exhaust. Problem was, the pipe wasn't being sold to the public.
Enter PHRP and their own version of the H-pipe. It pretty much mirrors the Shelby piece, being CNC bent and cut stainless tubing with a perpendicular, smaller diameter pipe section welded in.
My plan deviated a bit, as I wanted to fully weld the H section to an extra stock catted X-pipe I purchased some time ago (seller went with long tubes). Here it was hanging around, on the left.
For reference, the stock X on the extra pipe I bought (catted X had ~ 700 miles on it).
I think the stamped X section is fixtured and machine welded, then a human touches up any questionable areas. Looks like a Friday at 3:00 weld, I know, but all the stock pipes I've seen look like this...
I wanted to see how close the H section matched up to the X since I planned on welding everything up. I noticed a few minor discrepancies...
The bend angles were off ~3* to 4* on each side. Not a problem were you to cut and clamp, but certainly an issue for welding. After a few moments of brainstorming I picked the two points that need to be sliced, tweaked and welded back up.
I then laid out my cut marks on the X-pipe assembly after overlaying the H on top of it.
Some quick fixturing to keep everything in place when done (using some stainless angles tacked into place) and I made my cuts...
A fully welded, '07-'09, factory catted H-pipe, after unclamping and removing all the tack welds...
Fast forward to yesterday for the install. I wanted to weld in a bung before switching my factory X for my new found H. After finding about the only spot left to add one, I marked, drilled and welded in a bung for my new hole.
2009 pipe on left, 2007 pipe on right, replete with bung. Note the mid-pipe hangers that Ford used on the early pipes but eliminated by MY 2009. More on that later...
The H-pipe assembly fit like a damn glove.
I don't like the idea of the lengthy exhaust system being held up from the exhaust manifolds to the mufflers on the other side of the axle with nothing but a clamped juncture to keep it all in place. I'd like to add the hangers Ford no longer uses (anyone with a cross member they want to sell please, shoot me a pm...).
Everything tightened up well as the system lined up as factory. I put in an old fox body O2 sensor into the extra bung until I pick up a wideband.
Upon fire up, I noticed some cackling I never had before after some quick blips of the throttle. Weird, as it went away (O2 sensors sending different voltages due to backpressure change?). To be honest, I was not impressed with the new tone - it really hadn't changed at all. Or so I thought.
I got cleaned up and took the car out for some runs. Talk about a shit eating grin. The burble/rumble emitted while under load is simply fantabulous. No drone, no warble, no cackle. Just a refined yet powerful song that begs you to turn around when you hear it. And to be clear, it is by no means offensive or intrusive. The sound now matches the car itself.
Anyone with a 2011 factory H-piped car should get a premium for one of these assemblies if they move to long tubes. It is that good!
Last edited by Tob; 09-30-2011 at 05:22 PM.
Reason: Edited just to say...I love this car!