Replace front-y without precats?
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Joined: Jan 2004
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From: Yardley PA
Replace front-y without precats?
Well, I finally ordered my Random-Tech converter for my somewhat stock L98 ('87 with some free mods). However, I'm still on the fence whether or not I should replace the front-y and lose the precats. I don't want to gut them based on the posts I've seen on this forum. Also, routing straight pipe through them sounds like a PIA and I'd rather buy a new pipe.
What do you all think? Is just replacing the main cat good enough, or should I go the extra mile and lose the precats? Is it really worth the trouble or is there so little gained from doing so I should just save my money. If it's worth it, where should I get the pipe (corvette america wants about $100 more than madvet - is it a better pipe)? I'm assuming this is a 2.5" pipe so correct me if I'm wrong.
BTW - headers aren't in the budget so that's not an option. Probably wouldn't help a stock motor that much anyway.
Thanks in advance...
What do you all think? Is just replacing the main cat good enough, or should I go the extra mile and lose the precats? Is it really worth the trouble or is there so little gained from doing so I should just save my money. If it's worth it, where should I get the pipe (corvette america wants about $100 more than madvet - is it a better pipe)? I'm assuming this is a 2.5" pipe so correct me if I'm wrong.
BTW - headers aren't in the budget so that's not an option. Probably wouldn't help a stock motor that much anyway.
Thanks in advance...
Team Owner
Joined: Sep 2001
Posts: 62,154
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
You can get a 2.5" mandrel bent Y and put that in place, the Main Cat is good enough to pass emissions by itself.
Headers will give you big gains, doesnt matter if its stock or not, the stock manifolds are very restrictive.
Headers will give you big gains, doesnt matter if its stock or not, the stock manifolds are very restrictive.
Le Mans Master
Joined: Mar 2001
Posts: 9,464
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From: Modesto CA
If you're considering buying the Mid-America piece...don't waste your time. It's NOT Mandrel Bent. Best thing to do, would to go down to a local muffler shop, and just have them replace the PreCats with pipe. I BELIEVE it's 2¼". THAT'D be the best bang for the buck.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Each part of your stock exhaust system (on an L98) is restrictive. So if you replace just one piece you will not likely get the max benefit.
Doing a 2 1/2" front Y, hi-flow cat, hi-flow cat back should net you a 20-25 chp gain.
If you live reasonably close to Trenton, NJ, give a call to Denny at Mufflex (link on my site). They are an excelent custom exhaust shop and he and his guys are real artists.
I had them custom fit my TPIS cat back, install my RT cat and custom build a mandrel-bent 2 1/2" SS front Y for about $300. And they spent over an hour of the three hours on the entire job cutting & welding the pipes in the TPIS cat back to get it to fit right. This was after I had returned the $199 front Y from MAM because it came in bent and mangled.
So, to see the max gains from your new cat do the 2 1/2" front y, unless you plan on doing FL headers. Then do a hi-flow cat back when possible to unleash the rest of the HP that's in there.
Doing a 2 1/2" front Y, hi-flow cat, hi-flow cat back should net you a 20-25 chp gain.
If you live reasonably close to Trenton, NJ, give a call to Denny at Mufflex (link on my site). They are an excelent custom exhaust shop and he and his guys are real artists.
I had them custom fit my TPIS cat back, install my RT cat and custom build a mandrel-bent 2 1/2" SS front Y for about $300. And they spent over an hour of the three hours on the entire job cutting & welding the pipes in the TPIS cat back to get it to fit right. This was after I had returned the $199 front Y from MAM because it came in bent and mangled.
So, to see the max gains from your new cat do the 2 1/2" front y, unless you plan on doing FL headers. Then do a hi-flow cat back when possible to unleash the rest of the HP that's in there.
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Joined: Jan 2004
Posts: 96
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From: Yardley PA
Thanks 65Z! Mufflex is about 10 miles away so I'll give them a call after the new CAT arrives. BTW - forgot to mention I already have a flowmaster cat-back, so this will be the final mods to the exhaust (unless I go with headers later on).
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Good deal.
You have the right idea to let them do the new cat along with the front Y, so everything mates up nicely.
You should see a nice HP gain with those exhaust mods along with a nice sound level increase.
You have the right idea to let them do the new cat along with the front Y, so everything mates up nicely.
You should see a nice HP gain with those exhaust mods along with a nice sound level increase.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
And you remove another major under floor heat source in the process.Either way you remove them should improve performance especially if they have some miles on them.Mine were fairly well clogged up.
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