MRT H-pipe: Replacement converters?

My car's had an MRT catted H-pipe:

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for a while now and seemed to be losing power, gradually, for some time. It dyno'd surprisingly low before the cam installation and afterward, the numbers weren't great but okay. I had it tuned locally a year ago and the car put down an okay 274HP but a recent dyno test showed it to be down to 260 again. This was done after failing an emissions sniffer test rather miserably (I had a WB connected on the dyno to see what the A/F was like and it's spot on...) Fuel trims are all right where they should be so the tune is fine. In order to pass emissions, I put the factory 4-cat H-pipe back on and not only passed emissions with flying colours, I'm sure the car has picked up power too. I can only think at this point that the MRTs cats, one or both, are clogging or otherwise done, even though I can't visually inspect the cats due to the pipe bends to be sure.

So now I'm debating what to do. I was thinking one of two things:

1) Obtain replacement cats for it (I believe they're Magnaflow parts originally) and have them welded in.

2) Go to a different midpipe, possibly a Bassani catted X.

I'm leaning towards '2' but would appreciate other opinions. Also, does anyone know the replacement catalytic part number for these if I do choose to go with '1'?

darkside03gt said:

I have read a thred or two concerning mrt cats. mrt had issues with there cat manufacturer because they would not warrenty the cats for ANY length of time. and i understand it mrt has stopped making there h-pipes because of this. they are not maganflow cats but you could get some and have them welded in. you could also go with catco.

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I think MRT is still offering that pipe (p/n 93B000 and the source of the pic in my first post.) I didn't know about the cat issue though. Interesting.

it is no suprise that you failed the sniffer test with your mrt h-pipe on since it doesnt have the charcoal pre-cats on it. ford installed them for a reason. I believe magnaflows catted x-pipe is 50 state legal but it is expensive.

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When the MRT pipe was new the car did pass the inspection that year. Of course, that was before the Comp 262AH cams it's got now. You could tell the cats were only so-so even when new though: In 06 when it was tested and the pipe was new and the cams stock, the numbers were:

40KPH
HC ppm: 52 (limit 52)
CO%: 0.02 (limit 0.29)
NOx ppm: 84 (limit 385)

Idle:
HC ppm: 41 (limit 150)
CO%: 0.0 (limit 0.70)

That was before the cams. After the cams, the idle HC was 772ppm. The 40KPH numbers were about the same as before. With the factory pipe on (with the cams):

40KPH
HC ppm: 7 (limit 52)
CO%: 0.01 (limit 0.29)
NOx ppm: 6 (limit 385)

Idle:
HC ppm: 7 (limit 150)
CO%: 0.03 (limit 0.70)

For reference, when I took delivery of the car and it was bone stock down to the spark plugs, the numbers were:

40KPH
HC ppm: 3 (limit 52)
CO%: 0.0 (limit 0.29)
NOx ppm: 4 (limit 385)

Idle:
HC ppm: 2 (limit 150)
CO%: 0.0 (limit 0.70)

So the cats, whatever they are, look shot and these cams really are pretty mild...

I'll check into the Magnaflow X-pipe as well. I thought I'd read than the cats on the Bassani X-pipe weren't reliable either.

darkside03gt said:

I just looked into the magnaflow catted x and its no longer listed as 50 state legal. that is very interesting and suprising that your car passed with only 2 cats and no charcoal canisters.

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Well, it did though it was close. Now however, it stands no chance with those same cats, probably due to a combination of the 262AHs and because the cats are done.

and you never said anything about having cams. i have heard of cars failing smog with stage one cams.

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Actually, I did mention cams in my first post:

"...It dyno'd surprisingly low before the cam installation..."

though I don't blame you for missing it. The Comps are pretty mild. The car idles at 750RPM with just a slight roughness and didn't lose any low-RPM torque at all. With two healthy, good quality cats, it would probably pass. Not sure the same could be said of, say, Comp's 278s.

Anyway, hopefully someone chimes in with thoughts on the Bassani pipe.