I have to replace the front Y pipe/ w cats and the catalytic converter. With all the products out there, which is best products for my 1989 stock Vette and where is the best place to buy it.

 

There are a few options in this area.
the original cat and precats were used to clean up the exhaust because the precats cleaned up one pollutant, and the main cat cleaned up the other two.
1. You can buy a Front Y pipe for an 85 that does not have precats and will fit your existing exhaust configuration. Then buy a 3 way obd II main cat with an air tube.
The advantage here is the 85 pipe is bigger tubing. The disadvantage here is your mufflers may be inadequate to silence your exhaust and resonance. The precats act like premufflers.
THe out here may be to install 12 inch glasspacks in the new Y pipe and silence it that way, but you are cutting a new stainless tubing pipe and installing a mild steel rustable piece in the middle....
2. you can buy a front Y pipe with the precats and just be stock.
3. You can keep your original Y pipe, gut the precats, and go with an obd II cat and use an aftermarket cat back system.
4. you can have a custom exhaust made for your car utilizing the glasspacks and universal obd II cat and have a set of mufflers of your choice welded on the custom pipes.
5. You can buy someone's used front Y pipe, cross your fingers that the precats are good and unobstructed, and then get a cat back system, using your original cat.
6. You can buy a complete exhaust from an LT-1 car and modify the smog pump tubes a little bit, but the cats are enormous.

First, did you get a pressure test on your cats and precats done before you scrap the pieces?
You may want to get that done. It will cost you around $50, but messing with the exhaust will cost you 15 times that much. Exhaust is an expensive proposition on a C4.
You may be able to put small cats in place of the precats, and eliminate the main cat, and use stock mufflers, or aftermarket mufflers. Beware: the drone of your exhaust may drive you to drinking excessively if you use aftermarket mufflers....
That being said, I have a pair of mufflers I am looking to sell for $150 + shipping I took off my car and I don't drink anymore.

 

Get a front Y without pre-cats and a Random Technology main cat. It is a tiny bit louder than stock, but makes the car run much better. You can leave the stock rear Y and mufflers on.

As for where to buy, I got my Y-pipe from CorvetteCentral, I believe, and the R.T. cat I got from a guy here on the Forum. The Y-pipe is not mandrel bent, but does have the welded bung for the o2 sensor. If you want mandrel-bent pipes, you should look at Magnaflow.
I used a stainless, 4-bolt band clamp on the joint and it has not leaked. Go ahead and replace the hanger while you've got the Y-pipe off. It's very easy. And, use new bolts on the cat's flange fitting.

That's the best I can tell you. Be careful and be safe.


Mike
'90 'vert

 

bought this one of that auction site for 264.00 shipped ... It is a magnaflow aluminized with mandrel bends. Very nice welds and I am extremely happy with it. For a 1990 california car but 89 is probably the same.

 

Yep. That's the good one. Nice job, Jeff.

 

Will they be real loud without cats?
What's the best muffler to run ?

 

NO. Absolutely not. They do add a little rumble because you've lost the pre-cats (which act like mini-mufflers). And, like I said, I changed the main cat to a high-flow Random Technology cat, so I don't know exactly what that Y-pipe would sound like with the stock main cat on it.

As for your muffler question, just keep the stock pipe and mufflers on and see how you like the sound of them with the new front Y-pipe. Mufflers, I think, are a personal taste. Some people like the Borlas, or Corsas, or Flowmaster, or MagnaFlow, or whatever. Some like 'em loud, and some don't.

 

Mine has the cats punched currently. If you punch the precats the resonate pretty bad, better to cut them off and add a straight pipe.

It's not very loud though.

 

Thanks