MRT Catted H
Thread Starter
2nd Gear Member
Joined: Dec 2006
Posts: 472
From: TEXAS
MRT Catted H
I was considering LTs and a catted X pipe but with the possibility of being stationed in a state where emissions are likely, I have chosen to just switch out the midpipe with an aftermarket to match my SLP LM1s.
I have been searching and listening ever since I bought my LM1s and seem to like the tone the MRT catted H offers.
Anybody else running this midpipe?
I have been searching and listening ever since I bought my LM1s and seem to like the tone the MRT catted H offers.
Anybody else running this midpipe?
Thread Starter
2nd Gear Member
Joined: Dec 2006
Posts: 472
From: TEXAS
TECH SAVANT
Joined: Dec 2006
Posts: 10,937
From: Saint Augustine, FL
I always find it bemusing that 99.44% of non-LT exhaust system discussions revolve around what the various options "sound like"--performance is rarely even mentioned.
I mean this as no disrespect to anyone's personal preferences and only offer it as anecdotal evidence that from a performance perspective which particular mid-pipe/catback combination one selects doesn't really matter--they all perform pretty much the same.
In fact the only difference I have personally observed is as I recently posted here or somewhere else--an X-pipe, with straight-through mufflers like Magnaflows, will pull more strongly from 5000 to 5500 rpm and up than will an H-pipe with any mufflers.
However if you never push things that hard it doesn't matter. I actually prefer the sound of an H-pipe with chambered mufflers, but I like teasing with the rev-limiter (got mine at 6500) more...
I mean this as no disrespect to anyone's personal preferences and only offer it as anecdotal evidence that from a performance perspective which particular mid-pipe/catback combination one selects doesn't really matter--they all perform pretty much the same.
In fact the only difference I have personally observed is as I recently posted here or somewhere else--an X-pipe, with straight-through mufflers like Magnaflows, will pull more strongly from 5000 to 5500 rpm and up than will an H-pipe with any mufflers.
However if you never push things that hard it doesn't matter. I actually prefer the sound of an H-pipe with chambered mufflers, but I like teasing with the rev-limiter (got mine at 6500) more...
4th Gear Member
Joined: Sep 2009
Posts: 1,481
From: NC
The X will pull better at high rpms, but how much better?
There are obviously variables that make it impossible to say how much better in a quantitative way for everyone. I would love to see dyno charts for a full bolt-on car with O/R H vs O/R X and vs catted H.
Personally, I am more interested in area under the curve than peak numbers, but it would be nice to see an apples to apples comparison.
There are obviously variables that make it impossible to say how much better in a quantitative way for everyone. I would love to see dyno charts for a full bolt-on car with O/R H vs O/R X and vs catted H.
Personally, I am more interested in area under the curve than peak numbers, but it would be nice to see an apples to apples comparison.
TECH SAVANT
Joined: Dec 2006
Posts: 10,937
From: Saint Augustine, FL
I agree 110% and have said often on these pages that I would gladly trade 10-15HP or more peak ("just before you shift") for a similar gain down where it can be used...
I have never seen any back-to-back comparisons of H- and X-pipes, however I have driven similarly equipped cars with each system and can report solidly (according to my almost 65 year old butt-dyno with over 50 years experience) that an X-pipe with straight through mufflers will pull strongly well past the torque and HP peaks, right up to the rev-limiter--while H-pipe/chambered setups are noticeably challenged when pushed much beyond those peaks.
I have done back-to-back testing re: cats, on my '92 M-45 cold-side supercharged Miata. Running 4-2-1 Jackson racing headers at 12 psi we ran 3 pulls with a "test pipe", and then 3 with the cheapest cat Advance Auto Parts had in stock. There was no meaningful difference in the curves, right up to 8000 rpm.
This is not to say that swapping out the (sometimes multiple) OEM cats for so-called "high-flow" cats will not produce gains, however the difference between a reasonable cat and none is little to nothing.
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BTW: We also ran with the "Indy" style foam air filter and cowl CAI vs. a velocity "stack" directly mounted to the s/c intake--again mostly nada with perhaps a slight edge to the filter and cowl intake...
I have never seen any back-to-back comparisons of H- and X-pipes, however I have driven similarly equipped cars with each system and can report solidly (according to my almost 65 year old butt-dyno with over 50 years experience) that an X-pipe with straight through mufflers will pull strongly well past the torque and HP peaks, right up to the rev-limiter--while H-pipe/chambered setups are noticeably challenged when pushed much beyond those peaks.
I have done back-to-back testing re: cats, on my '92 M-45 cold-side supercharged Miata. Running 4-2-1 Jackson racing headers at 12 psi we ran 3 pulls with a "test pipe", and then 3 with the cheapest cat Advance Auto Parts had in stock. There was no meaningful difference in the curves, right up to 8000 rpm.
This is not to say that swapping out the (sometimes multiple) OEM cats for so-called "high-flow" cats will not produce gains, however the difference between a reasonable cat and none is little to nothing.
---------------------------------------------------
BTW: We also ran with the "Indy" style foam air filter and cowl CAI vs. a velocity "stack" directly mounted to the s/c intake--again mostly nada with perhaps a slight edge to the filter and cowl intake...
4th Gear Member
Joined: Sep 2009
Posts: 1,481
From: NC
I hate the sound of the O/R X with my chambered mufflers, but have wondered if I could measure any change in trap speed on my car by swapping in an O/R X before I go to the drag strip??? Other than the obvious run up to redline in 1st gear, I am between 4200rpm - 6300rpm the rest of the pass.
The MAC ProChamber is probably a good compromise. I have been running my O/R H for about 5 months now.
Side note: I'd love to know more about your SC Miata! My wife's 2002 Miata is about to be replaced, and I want to make an autox car out of it.
The MAC ProChamber is probably a good compromise. I have been running my O/R H for about 5 months now.
Side note: I'd love to know more about your SC Miata! My wife's 2002 Miata is about to be replaced, and I want to make an autox car out of it.
Last edited by TRUEBLUE3934; Jan 19, 2012 at 05:28 PM.
TECH SAVANT
Joined: Dec 2006
Posts: 10,937
From: Saint Augustine, FL
I never well-documented the cold-side supercharger as it was my last major project before having a windfall profit from an unexpected job and buying the Mustang--however here's a link to my Miata pages, pretty much abandoned in late 2006...
I had three at one point, here are the last two:
I had three at one point, here are the last two:
Last edited by cliffyk; Jan 19, 2012 at 05:59 PM.
6th Gear Member
Joined: Feb 2005
Posts: 5,361
From: Vegas
hey man just FYI i am out of state military stationed in nevada. my GT is still registered in connecticut as well as a connecticut drivers license. i get an out of state military exemption aka lt's with o/r x 
so check out your home of record laws before registering in the state you get stationed at.
so check out your home of record laws before registering in the state you get stationed at.