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Opinion wanted on Exhaust Mod

2K views 27 replies 18 participants last post by  Sixlitre 
#1 ·
I am thinking of having my exhaust modified by an exhaust shop. I want to cut in front of the first factory cat and behind the factory muffler and replace all that with a (one) high flow cat and performance muffler. Reuseing the stock "Y" and tail pipe. Will this benefit me, as running and breathing better? I am also trying to reduce the heat off my herculined floor a bit as well. I didnt want to remove manifolds and go the header route, I also wasnt thinking the whole Bassani thing was for me either mainly due to cost. I have read alot of the exhaust threads but havent found what I was lookin for. This thing is my DD, not looking for anything phenominal just better. Any suggestions or input would be greatly appreiciated.
 
#2 ·
Are you a 5.0 litre or a 5.8 litre ?

Do you know the exhaust shop is going to tell you to p!$$ up a rope ? They are not allowed, by Federal law, to modify or cut up a cat.

You might get them to replace it with a Catco single cat system (that bolts right onto your 5.0 litre's manifolds), but they won't be butchering anything to your liking, with regards to the cat.

If you are a 5.8, it's pretty much Bassani and trying to find the best price you can, or building your own Y pipe, like s1120 has a thread on right now.

Sixlitre
 
#3 ·
I believe it is a federal offense to modify any working cat system, thats what the big posters in the exhaust shops say... that being said it will make the whole thing flow better for sure, even better if you get a bigger tailpipe too (behind the muffler) There are other companies who offer the y-pipe with a cat, do a search.

Or you could chop off the cats yourself and say someone stole em, then get it all done the way you want..... just an idea.....don't get pulled over on the way to the shop!
 
#4 ·
Im a 5.8 and I was hoping that Bassani wasnt my only option. Do any other companys offer a direct replacement Y pipe with a cat for a 5.8? Seems like there are much better options with the 5.0. I guess I didnt really want to try to do the exhaust myself. If there is one thing I hate to work on.... I also didnt know that the Feds wont allow a cat replacement if the old one isnt defective. I did hear that replacement cat had to be designated for correct cubic inches and keeping documentation of that was a good idea.
 
#21 ·
I also didnt know that the Feds wont allow a cat replacement if the old one isnt defective.
1. The vehicle is missing a converter
2. A state or local inspection program has determined that the existing converter needs replacement
3. Vehicles manufactured prior to 1996 must have more than 50,000 miles, and a legitimate need for replacement must be established and documented
4. In cases of OBD Il-equipped vehicles (1996 and later), the O.E. manufacturer's 8-year/80,000-mile warranty must have expired and a legitimate need for replacement must be established and documented.
Please note that Federal law prohibits removal or replacement of a properly functioning O.E. converter.

When replacement of the converter is appropriate (as outlined above), the E.P.A. further requires that:

1. It be installed in the same location as the original
2. It be the same type as the original (i.e., two-way, three-way, three-way plus air/three-way plus oxidation)
3. It be the proper model for the vehicle application as determined and specified by the manufacturer
4. It be properly connected to any existing air injection components on the vehicle
5. It be installed with any other required converter for a particular application
6. It be accompanied by a warranty information card to be completed by the installer.

(if you need a reason, get it hot and hit it with a hammer) dropping my vette's hot cat on speed bump did the trick for me, too bad i didn't want it broken.
lots of people replace them with other than stock and few get in trouble for having a slightly different setup, for my vette i'm going from 3 cats to 1 when i replace the Y pipe just because new ones are better than they were in 85 and one can do the job of the three 23 year old ones, if it passes and it's present i don't think you'll get too much hassle over it
 
#6 ·
Im not unhappy with my power really just wanted less floor heat and better sound. Maybe I should just do a cat back, even though Ive read it would be against sixlitre's advice.
 
#13 ·
A catback will add to the sound, although I am happy with no muffler (and stock cats) , it's way quieter than my roommate's 4.7L jeep with a single chamber flowmaster. Just having the shop fab you a turndown after the 2nd cat will be super cheap too.

For floor heat, just get some exhaust wrap for the tubes, I think they make strips big enough for cats too, just secure it with a hose clamp. Find that at any good car parts shop.
 
#9 ·
almost any exhaust shop will do it if you tell them the car is for off road use only. roll in with no plates or inspection sticker.


i did almost exactly what you are looking to do. the shop cut the stock y pipe just before the cat, ran dual pipes into a lightning muffler.
 
#10 ·
So I guess the new question raised is how to quickly ruin a cat, huh?

Could always slam it on a rock (or get stuck on a stump like me :D ) and get it a lil messed up. Of course, its gonna have to be a big rock or stump because mine just dented the heat shield.
 
#14 ·
just dont be stupid and ask a midas or something to do it. Find a local guy who owns his own garage and there are very few tihngs that they wont do. Most of them (Atleast in my area) dont give a **** what they put on your truck.
 
#17 ·
If they are high flow cats they will flow better, I doubt they're worth the $50 or more. Unfortunately there isn't a way to "test drive" a truck with them, but I wouldn't replace factory parts unless they were broken, IMO.

In general, if you keep the engine at 8.5 compression ratio, I doubt you can make any more than 270 to the rear wheels if N/A. And thats after spending multiple thousands of dollars for a mere 100, maybe 120hp over stock to the rear wheels. If you like fast, I think either pre emissions or cars are the way to do it. Maybe a big block!
 
#19 ·
Nice pic

just think, if you'd had duals you'd have twice the expense and trouble replacing twice the damage (except it'd be worse because duals ALWAYS hang lower).

C-dub

I used Catco, plain flow 3" cat because;

a.) it was $55.00

b.) Going to any single 3" cat, over two 2 1/4" cats is going to improve flow. Mine did, in a huge way ! (but like Axlesofevil suggests, don't let that stop you from shopping for the best at the best price you can get).

c.) it was $55.00 ;)

Shadybrady19

Amen to that ! Mine is exempt from here on in :chili:

Sixlitre
 
#22 ·
Well thats just crazy! Thanks for the input everyone but now Im not sure what I want to do, I honestly didnt think it would be nearly this complicated. I may just stop at the exhaust shop and run it by them...worst case they say no ...right?
 
#24 ·
I cut mine off myself before the cats. I then took it to a shop and asked them to run me a 3" exhaust with a Flowmaster muffler. They used a Flowmaster y-pipe. I just told them the truck was mostly for off road.

I don't know if that'd work for you or not. The county I live in here in Idaho doesn't have emissions inspections, and we're pretty rural so no one gives a rip for the most part.

Good luck!
 
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