True Duals or Single Cat
Thread Starter
Burning Brakes
Joined: Mar 2010
Posts: 1,094
Likes: 68
From: Providence RI
True Duals or Single Cat
All,
Trying to decide on what to do. 91 L98 with TPIS long tubes, TPIS Y-pipe, and Corsa Cat-back. My cat is shot (mangaflow aftermarket, honeycomb exploded when my pick up coil died and the unburnt fuel blew the f--- out of it.)
So first off, I need emissions. The car failed with the busted cat, but that was with the 350 motor and now a 383 is going in.
I think true dual exhaust is cool, esp with corsas on the back, but it makes the rear y-pipe useless (so what...) I would have a performance exhaust shop (fantastic) mate up my long tubes to the mufflers with two cats inbetween. This would be the last step and it would be removable somehow. Maybe a clamp at the header and one at the back end of the cat?
The other option is to get another magnaflow for an early TPI (4 bolt flat flange on the front to match my TPIS Y-pipe with the same fitting) and bolt it all together myself.
I don't mind paying a shop for mount it all up as I can do the headers without a problem.
Another issue is the cost of cats if i went true duals. My old magnaflow cost like 120 shipped to my door. Two cats to get welded in would be more expensive. If i go true duals, what cats?
Thanks,
Mike
Trying to decide on what to do. 91 L98 with TPIS long tubes, TPIS Y-pipe, and Corsa Cat-back. My cat is shot (mangaflow aftermarket, honeycomb exploded when my pick up coil died and the unburnt fuel blew the f--- out of it.)
So first off, I need emissions. The car failed with the busted cat, but that was with the 350 motor and now a 383 is going in.
I think true dual exhaust is cool, esp with corsas on the back, but it makes the rear y-pipe useless (so what...) I would have a performance exhaust shop (fantastic) mate up my long tubes to the mufflers with two cats inbetween. This would be the last step and it would be removable somehow. Maybe a clamp at the header and one at the back end of the cat?
The other option is to get another magnaflow for an early TPI (4 bolt flat flange on the front to match my TPIS Y-pipe with the same fitting) and bolt it all together myself.
I don't mind paying a shop for mount it all up as I can do the headers without a problem.
Another issue is the cost of cats if i went true duals. My old magnaflow cost like 120 shipped to my door. Two cats to get welded in would be more expensive. If i go true duals, what cats?
Thanks,
Mike
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
ANY late model cats can be welded in for true duals and a solid welded in system and leave 'em.
There is absolutely zero reason to take cats out and go thru all that silly sht pullin 'em and puttin 'em back...they do not harm anything, so whats the point? new cats are so free flowing you cannot even measure any back pressure thru them. Old stories 20 yrs ago...sure, pull em first chance. Now, no reason to do that.
I'd go duals, 2 cats welded in, weld in the entire system to the back and forget it. IF anything gets bolted...flange the mufflers so they can be dropped and a muff eliminator stuck in for race day. Corsa makes a good eliminator, 1 inlet 2 real exits.
There is absolutely zero reason to take cats out and go thru all that silly sht pullin 'em and puttin 'em back...they do not harm anything, so whats the point? new cats are so free flowing you cannot even measure any back pressure thru them. Old stories 20 yrs ago...sure, pull em first chance. Now, no reason to do that.
I'd go duals, 2 cats welded in, weld in the entire system to the back and forget it. IF anything gets bolted...flange the mufflers so they can be dropped and a muff eliminator stuck in for race day. Corsa makes a good eliminator, 1 inlet 2 real exits.
Thread Starter
Burning Brakes
Joined: Mar 2010
Posts: 1,094
Likes: 68
From: Providence RI
Lees, Always appreciate your input. I thought it would be easier to service with the headers being able to be unbolted and maybe another clamp at the muffler? That way in case I had to remove the exhaust for various repairs it would be doable?
What cats dol you recommend? My TPIS long tubes are 3" at the collectors.
Thanks,
Mike
What cats dol you recommend? My TPIS long tubes are 3" at the collectors.
Thanks,
Mike
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Mike, flanged at the collector is fine, for the reasons that you specify. I'd weld from there back...to the far end where IF you wanted that bump from no mufflers, I could unbolt the muffs and stick an eliminator pipe in its place...I guess if hung properly you could actually bolt the entire system together...
I like welds...and I have a sawsall
cats? they are all pretty much free flowing these days. There are some that are better than others of course...but at what $$$ ? thats the issue. They range from $125 to $350ea and some are limited to what state you are in..what will FIT will ultimately decide this.
I'd buy a brand name or something from a reputable seller, chain store or trusted online source. I just have not heard of any disappointments in the cat supply in the last few yrs since the technology seems to be thru the entire industry. With true duals...there is less gas trying to pass so the build up of back pressure is greatly reduced. Trying to stuff 8 cyl worth of gas thru a similar size pipe might create a mild build up...but likely not enough to choke the engine down.
I like welds...and I have a sawsall
cats? they are all pretty much free flowing these days. There are some that are better than others of course...but at what $$$ ? thats the issue. They range from $125 to $350ea and some are limited to what state you are in..what will FIT will ultimately decide this.
I'd buy a brand name or something from a reputable seller, chain store or trusted online source. I just have not heard of any disappointments in the cat supply in the last few yrs since the technology seems to be thru the entire industry. With true duals...there is less gas trying to pass so the build up of back pressure is greatly reduced. Trying to stuff 8 cyl worth of gas thru a similar size pipe might create a mild build up...but likely not enough to choke the engine down.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
A tip about cats... California has mandated that replacement cats must meet OBDII standards for durability.
The problem? They cost more upfront. The advantage? They last so much longer that they pay for themselves in no time flat.
I am with Leesvet on this. Do a dual system with bullet cats and be done with it. You will pick up real power with this setup, too. 20hp, or so. That's how restrictive the OEM single cat system is.
The problem? They cost more upfront. The advantage? They last so much longer that they pay for themselves in no time flat.
I am with Leesvet on this. Do a dual system with bullet cats and be done with it. You will pick up real power with this setup, too. 20hp, or so. That's how restrictive the OEM single cat system is.
Burning Brakes
Joined: Aug 2011
Posts: 878
Likes: 2
I've done a lot of research and made some phone calls including TPIS and Random Technology. Unless you're running a monster cube engine you don't need duals i don't care what anyone tells you. Your TPIS LTH with the TPIS y pipe into a Random Technology main cat will work great. Call TPIS....call Random Technology. In fact you have the EXACT same exhaust set up i'm going to change to. You can unbolt and drop all of it any time you need to. Why weld it?
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
I love my Pypes true duals, everything fit perectly
http://forums.corvetteforum.com/c4-t...s-reviews.html
http://forums.corvetteforum.com/c4-t...s-reviews.html
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Burning Brakes
Joined: Aug 2011
Posts: 878
Likes: 2
I love my Pypes true duals, everything fit perectly
http://forums.corvetteforum.com/c4-t...s-reviews.html
http://forums.corvetteforum.com/c4-t...s-reviews.html
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
I'll never tell,, but I would say that true duals WITH CATS might make sense.
I had the cats and they seemed to work well but they really got hot due to the unburned fuel in the exhaust on my car, hence my cam swap
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
I've done a lot of research and made some phone calls including TPIS and Random Technology. Unless you're running a monster cube engine you don't need duals i don't care what anyone tells you. Your TPIS LTH with the TPIS y pipe into a Random Technology main cat will work great. Call TPIS....call Random Technology. In fact you have the EXACT same exhaust set up i'm going to change to. You can unbolt and drop all of it any time you need to. Why weld it?
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 79
From: Monroe OH
NCM Sinkhole Donor
I've done a lot of research and made some phone calls including TPIS and Random Technology. Unless you're running a monster cube engine you don't need duals i don't care what anyone tells you. Your TPIS LTH with the TPIS y pipe into a Random Technology main cat will work great. Call TPIS....call Random Technology. In fact you have the EXACT same exhaust set up i'm going to change to. You can unbolt and drop all of it any time you need to. Why weld it?
with true duals, unless you place an x-pipe close to the headers, you will loose the exhaust scavaging and sacrifice some power. I tried true duals several years ago and lost power and quick engine spool up. Went back to y pipe up front then into single then y at the rear.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Team Owner
Joined: Dec 2000
Posts: 21,094
Likes: 282
From: Phila., PA burbs
I love my Pypes true duals, everything fit perectly
http://forums.corvetteforum.com/c4-t...s-reviews.html
http://forums.corvetteforum.com/c4-t...s-reviews.html
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
with true duals, unless you place an x-pipe close to the headers, you will loose the exhaust scavaging and sacrifice some power. I tried true duals several years ago and lost power and quick engine spool up. Went back to y pipe up front then into single then y at the rear.