Hello all,

I need a little help here. I have a 1992 RS B4C with the 5.7 TPI motor. I was thinking of putting a cat back exhaust on it until I looked under the car. Apparently at some point, someone welded the factory Y pipe to the main pipe that runs the length of the car.

I'd like to scrap this Y pipe and replace it with a factory unit if possible. It's the dual cat piece and I'd like to find a used one as I'm sure someone has taken one of these off somewhere along the line to replace it with a set of headers and off road Y pipe. They test both visually and with a sniffer for emissions here, so an off road pipe is a no go.

Also, what years are interchangeable? Can I use a Y pipe from an earlier dual cat car, or are they year specific? Also, I have a single cat Y pipe from a 1988 350 IROC-Z. Will this work by any chance and how much more restrictive is it than the dual cat piece? It would be easy if I could just unbolt and replace everything but I have to cut and hack everything off so there won't be any going back once I start.

Any help is greatly appreciated!

 

You might try the "Parts Wanted" classifieds on this Board, as well as searching the "Parts for Sale" forum.

As far as I know, all dual cat exhaust was the same (at least up to through the cats). Comparing factory-to-factory, the dual exhaust was worth about 10 HP over the large single cat exhuast.

More expensive than used and probably better than stock is the Catco replacement. http://store.summitracing.com/largei...g=cto-4153.jpg

 

Thanks for the response, I appreciate it. I didn't know that someone made a complete replacement Y pipe for these cars.............only problem is the price...........I'm trying to keep this a low dollar project car at this point.

I'll keep my eyes out for a stock piece in the for sale section and keep looking locally too. Everything works fine now, but I'd just like to replace it at some point for a little more perfomance. Right now the car ran a 13.92 with just a Flowmaster muffler and K&N filters.

 

Here's another option for ya........

https://www.thirdgen.org/forums/exha...w-y-pipes.html

 

Thanks, but unfortunately I can't use that one.............we have to pass both a sniffer and visual inspection here in DE. I'm pretty sure it would pass the sniffer, as my previous Z did with out the cat or AIR pump, but not the visual.

It's a shame cause I'd love to run that...........

 

Cut at the weld and re-assemble with new parts using one of these at the joint. They're available in a variety of sizes, no doubt some one or another of them can be made to do the trick.

 

The thread CraZ-28 linked discussed a y-pipe that is available to connect factory manifolds to a stock single cat. With a single cat, you would pass visual and sniffer. Personally, I think that is a poorly designed y-pipe, basically a "T" pipe where the passenger side joins in. The dual system is a little better where they join after the cats (but still not perfect).

You didn't say how the previous owner connected the downpipes to the I-pipe. But, if they did it with straight pipes, like sofa said, cut them out, put in a couple of 2-1/2" cats. If they put in a "Y" with a single pipe back to the I-pipe, cut out the piece of pipe and put in a single 3" cat.

Since you have a single pipe from an '88, that would probably be the least expensive option for you. Buy a direct-fit cat for it like the Catco 9118, and then a cat-back for the same application ('86-'90 TPI single cat).

 

The previous owner just hacked this exhaust together. The pipes look very nasty and they just spliced some tubing in with a stick welder to join the Y and I pipes together. Looks terrible and I just want to do away with the whole unit eventually, but it does work and this is a budget project for the time being. I can't imagine its too restrictive either since the car appears to run pretty well. I'm about performance and appearance in that order for this car.

I'm going to keep looking for the dual cat Y pipe for awhile..........again this is something that doesn't need to be done tomorrow and I'd rather keep the car as original looking as possible. There is plenty of other free/cheap things I need to do first. If I can't find anything, I'll use the pipe off the 88 Z as it still has the converter which is already hollowed out.