Another thread on exhaust....

I have a 93 LT1 coupe. A PO put in LT headers, and took out cats, and from the resonator back appears to be original. No major mods to the engine as far as I can tell aside from a bored out TB (52mm) and all the emissions stuff removed. The issue is that I suspect the drivers side muffler has an obstruction, it has a bit of a bulge to it and when putting your hands over the tailpipes, there is a noticable different in the amount of pressure felt (drivers side being much less than pass side). Baffles are probably messed up due to the lack of cats. So I am looking to only replace the mufflers, I cannot afford a full system and not sure if there is any reason to. I have seen a lot of write ups on full exhuast system changes, but not much on just swapping out mufflers. What is the most economical solution here to get some better performance and sound without breaking the bank. Will aftermarket mufflers survive the lack of cats or will i eventually have the same issue? I think muffler eliminators would be too much for me expecially with LT's and no cats. I have access to a custom exhaust shop, so I dont need anything that has to be bolt on, just want a a muffler that welds in place and keep the same mount to the chassis. All I seem to be able to find it cat back systems or axle back systems for big money when all I really need are the mufflers/tailpipes.

 

When I used to have rear-exit exhaust, I really liked dual 3", slash-cut resonators. I'm pretty sure they're still sold.

Because LT's have that retangular tip, I think there's more flexibility. A recent clip of chamber pipe proves a valid option. I would also suggest 12" glass packs BEFORE the last bend as something to consider. The later is very inexpensive.

If it turns out too loud, I really like the resonated x-muffler Magnaflow sells. It has a very good sound..and may give a slight bump in performance (over the stock resonator). I would also suggest -- since you've posted about the smell that re-installation of convertors would be the best option. In fact, you might want to try that -- in conjunction with eliminators out the back. Then, add glass-packs if necessary [later]. Just get universal bullet cats as sold by several manufacturers.

Those are really the best options price-wise. I would also suggest they are the least likely to cause drone -- if you'd like a louder exhaust. If not, you're probably gonna do best by returning to stock components.

 

Thanks for the suggestions, I will look into those options. I found a site that sells the Xpipe and it also sells magnaflow mufflers by themselves!

Will the cats work without the airpump? If I recall correctly, the life of the cat is reduced quite a bit becuase it doesnt come up to temp fast enough. I dont have any of that stuff (the piping, check valves, vacuum tubing, etc) to go with it. Also, there are aftermarket valvecovers and when I went to add the EGR back on, the @#$%@ valve cover was too big and the pipe from the header to the intake wouldnt fit. So it all just adds up into a multi thousand dollar ordeal to bring the emissions stuff back.

 

Yes, CATs with work w/o an airpump...and quite well too. They just don't heat up quite as fast.

You didn't mention if your motor is still a 350, but I assume it is. As such, ceramic cats would still perform well w/o significant shortening of their life. If you want to be sure, consider metallic spun cats. I've been using them on my 383 -- with headers -- for 3 years now. They cost $30-$40 more per unit but are worth it. Use the model number desired and search on ebay to determine "going price".

http://www.magnaflow.com/02catalytic...SPUN PRE-OBDII

Hopefully, the link above will work -- even though it has a forward slash in it. It's a link to the pre-ODBI metallic converter line-up. 2.5" or 3" will work on your LT. (BTW..I actually used the 45-deg bend models. They worked quite well, to get exhaust piping over into the belly.

There are aftermarket valve covers. I'd do a search and/or start a new thread for feedback on that. I bought some super expensive covers for bling. Most people wouldn't want to spend that much.

 

Not to hi-jack but do the LT1 exhaust systems resonate/drone when going to hi-flow cats & mufflers??

BTW, I had Magnaflows (with Y-pipes) on my '88 and loved the sound, just grew to dislike the drone.

 

LT1's don't really seem to have as much problem with drone as L98's IMO. I've seen a longtube header car w/o cats...and factory mufflers. Zero drone.

I've seen factory manifolds with no cats, center Magnaflow x-muffler and eliminators. Health...but no drone.

I bet Flowmasters, DynoMax, and Magnaflow rear muffers would drone though...even on an LT car. I'm telling ya...I think it's those darn oval canisters...when there's no internal packing. (all sport mufflers are sans packing.)

With glass packs and chambered pipe, there's no real sound chamber to form that drone frequency. Corsa's baffle/shape around that. Magnaflow x-mufflers have the internal packing necessary to deaden harmonics. And, glass packs are just to small (bodied).

 

Thanks for the very interesting info...

My "new" '88 is pretty quiet and looks like it has OEM front Y & cat and close to stock mufflers, though both pipes in each muffler seem to have exhaust flow??

I'd like to open up the system a bit but avoid the drone. I've thought about the LT1 style with dual cats & resonator with current mufflers or Corsas if needed.