Cat seems clogged - rest is pretty rusted.

[MegaHertz]

So my exhaust is showing its age. I'm pretty sure the whole exhaust is original except for the thrush muffler which went on in place of the stock one with many adapters and clamps after the original developed a large hole a few years back. There are several holes on the tailpipe as it exits the muffler and i haven't really looked closely at the rest. The Cat is what I believe to be the cause of my higher rpm problems of not being able to rev past 4k under load with no pull after 3.5k. I noticed some rattling when i revved it up sitting in neutral.

So I'm pretty sure the cat has gotta go. I've noticed stock fitting cat units with all the piping are around 200+. Bare cats a little under 100 with some cutting and adapting needed and possible loss of o2 bungs. Given the age of the rest of the exhaust system I'm thinking of doing it all from the headers back. Given the rest of the system going on 15 years & the last 6 or more being in northeast winters It seems worth the effort to do it all. I'd also love to get a nice look at everything seeing as I'm leaking some oil somewhere out the rear of the engine (which I keep telling myself is normal for these cars as they age) but I'd still like to clean everything up a bit and see whats going on.

I don't plan on any forced induction mods - maybe heads and cam down the road. Would a 2.5" all the way be enough? Should I go 3" Also whats the best bang for the buck headers / cat / catback setup that I'm going to be able to fit together without welding? And I would hate for it to be in any way raspy.

I'm trying do the whole exhaust setup for under $1k with me doing the work but little fabrication needed other than some minor cutting and clamping.

I've found many options for headers and cat back with pacesetter and magnaflow winning out in the price department in those categories in my initial searching. I am finding less in the 'midsection' containing the cat and its associated piping. I definitely want to keep the diameter consistent and a bit bigger than stock.

I'd much rather sink the money into shocks, bushings and tubular suspension components at this point but I will need a functioning cat to pass inspection come may and I've already got an o2 heater code for the post cat sensor and a egr code.

[skimphish]

Re: Cat seems clogged - rest is pretty rusted.

get pacesetter headers, a hi-flow magnaflow cat (like $70 new on ebay), and a stock ls1 catback (i got mine for $100 shipped to me). dont worry about the o2 sensors, you can have bungs welded in since you need the o2's. Honestly just get all of this and take it to an exhaust shop and have them weld it up for you. I had a guy weld mine up for like $50. My total exhaust setup (before the turbo) was like $375. That was used pacesetter headers, new cat, and a stock ls1 catback (2.75" all the way).

for the codes you are probably gonna need to go get new o2 sensors. depending on ur mileage id probably just get new ones all the way around. and the egr may need replaced as well.

[MegaHertz]

Re: Cat seems clogged - rest is pretty rusted.

Well I like the idea of pacesetters (hoping to find them used but the black ones aren't too bad in price) and the LS1 takeoff. I'm thinking total budget could be around 600. What did the shop do with the y-pipe? Weld the new cat into the stock one or is there a larger diameter one I can get?

I've realized once I get all the parts I won't be able do the whole system as it will be too cold to work on it so tomorrow I'm cutting out the cat and putting either a pipe or muffler in its place. Thinking this is the last weekend I can get away with working without the hands going numb as the garage is full of crap and thus the driveway is my garage. The sensor can live with it until the spring time and I can do the rest of the job right while gathering parts without time pressure.

[skimphish]

Re: Cat seems clogged - rest is pretty rusted.

You can come in lower than $600 if you just wait and shop around. Check all the forums, V6 and V8 forums, and you will be able to find your parts. Just post a "wanted" section on LS1tech and I assure you that you will have plenty of responses of people wanting to get rid of their stock catbacks. And the more V6 forums you go look at the easier you will find a cheap set of used headers.

The headers will come with a new y-pipe. You are gonna need a 3" cat to get welded to the y-pipe. Then you will need to buy a 3" u-bend to make an S-pipe. Just cut the u-bend in half, flip one side and have it welded to make an "S." Then the LS1 "catback" goes in. In all reality I suggest getting a lap band that connects the s-pipe to the catback. This makes it to where you can drop the front half of the exhaust and get it out of the way easily. There have been several times when I need to do this to make live easier. They make 2.75" to 3" lap bands, so just grab one of those and connect the s-pipe to the catback.


This is just how my exhaust is setup, minus the cat. I have a cutout instead, when I put the turbo on I had to delete the cat and I was too cheap/lazy to buy a new cat when I sold the turbo. lol. Its nice and simple, sounds good, and most importantly it's cheap. :D

[MegaHertz]

Re: Cat seems clogged - rest is pretty rusted.

Well I got the cat today - magnaflow 3" with dual o2 bungs. Gonna have the shop near my work put it in next week as a holdover until the spring when I'm planning on doing an LS1 takeoff with pacesetters and the 3". I can't weld yet and didn't want a 6 clamp job going on like happened with the muffler. Right now the exhaust just sounds awful - I cut an inch or so sized hole in the exhaust right before the cat to test the cat issue and I can definitely pull into higher rpms than before but damn its loud and just nastily hisses when you get on it. Between this and the suspension I should have some fun projects for springtime.