2002 GT, stock cat-back, factory manifolds.
Fit was a bit concerning. The guy installing it said the passenger side pipe was upwards of an inch too short, causing the rest of the cat-back on the pass side to be pulled forward a bit. The pipe sits very close to the floor pan on the passenger side where it kicks out of the manifold (1/2" max) and the cats themselves snug up very close to the floor. Between the tops of the heat shields and the floor is maybe 1/4" at some points. I thought it'd be banging under there as the engine torqued around but it didn't seem to have, yet at least. Because it snugs up under the car well there's no concern at all about dragging over speed bumps... No exhaust leaks, yet. I supplied some high-temp, sensor-safe "copper" RTV to be applied to all ball-joints and MRT supplied a fresh pass-side manifold gasket (though I bought a couple from Ford anyway...nice to have...)
The factory H is a heavy mofo compared to the MRT part....at least twice the weight of the MRT. The MRT is made from a much thinner grade of stainless and, of course, only has two (high flow Magnaflow, as it turns out) cats.
The exhaust note change was subtle but definitely welcome. It's got a lower tone, more "burbly", even at idle. Accelerating gives a very pleasing amplification of the factory exhaust note, which is a good thing. Sounds meaner, more "stacatto". As the cat back is stock, there's no drone and nothing offensive on the highway.
As far as performance, the butt-dyno likes it but I'm not going to venture numbers. It's not huge as is to be expected with factory logs and cat-backs but it's noticeable. This is another one of those "over 3500 is just comes to life" mods. In a week I should be able to pop it on the dyno to see if I bettered my current 247HP.
So far, after a day, I'm more pleased than disappointed. The fitment (pipe length, proximity of the pipe to the frame and the cats to the floor) are a bummer but I love the sound and the feel now. Can't wait to dyno it.
Fit was a bit concerning. The guy installing it said the passenger side pipe was upwards of an inch too short, causing the rest of the cat-back on the pass side to be pulled forward a bit. The pipe sits very close to the floor pan on the passenger side where it kicks out of the manifold (1/2" max) and the cats themselves snug up very close to the floor. Between the tops of the heat shields and the floor is maybe 1/4" at some points. I thought it'd be banging under there as the engine torqued around but it didn't seem to have, yet at least. Because it snugs up under the car well there's no concern at all about dragging over speed bumps... No exhaust leaks, yet. I supplied some high-temp, sensor-safe "copper" RTV to be applied to all ball-joints and MRT supplied a fresh pass-side manifold gasket (though I bought a couple from Ford anyway...nice to have...)
The factory H is a heavy mofo compared to the MRT part....at least twice the weight of the MRT. The MRT is made from a much thinner grade of stainless and, of course, only has two (high flow Magnaflow, as it turns out) cats.
The exhaust note change was subtle but definitely welcome. It's got a lower tone, more "burbly", even at idle. Accelerating gives a very pleasing amplification of the factory exhaust note, which is a good thing. Sounds meaner, more "stacatto". As the cat back is stock, there's no drone and nothing offensive on the highway.
As far as performance, the butt-dyno likes it but I'm not going to venture numbers. It's not huge as is to be expected with factory logs and cat-backs but it's noticeable. This is another one of those "over 3500 is just comes to life" mods. In a week I should be able to pop it on the dyno to see if I bettered my current 247HP.
So far, after a day, I'm more pleased than disappointed. The fitment (pipe length, proximity of the pipe to the frame and the cats to the floor) are a bummer but I love the sound and the feel now. Can't wait to dyno it.
) Unfortunately I don't exactly know how much of the improved sound & perfomance is attributable to the H-pipe vs. the Dynomax Super Turbos since they both went on at the same time. Muffler shop said they also had to fab it a bit to make it fit. They were surprised to find that the stock h-pipe had 6 cats! 
I definitely gained some HP. This many butt-dynos can't be wrong.
I had the same impressions when I installed mine. I still haven't been to a dyno though. 
As "issues" go, what turns out to be just a tight fit is really nothing at all.
I was thinking of checking out some mufflers. I'd rather not do the whole cat back ($US600 is alot for mufflers and pipes and my motor doesn't move enough air to need pipes bigger than stock). Sean Hyland's book says that the factory Bullitt mufflers, specifically, are a "good muffler", impying that they are different from the base GT. Is this true? How much louder than a GT is a Bullitt? Can these mufflers (only) be sourced from Ford and can they be easily & reliably welded into the factory system?
