The catback is all rusted out on my 88 IROC convertible. I did some googling but can't get a straight answer. What is the cheapest OEM catback system out there, or closest to OEM?

 

OK, let's sort this out...

Do you want "cheeeeeeep"?

Or, "OEM"?

Or, "close to OEM"?

Might come out to 3 very different things.

Personally I don't find "cheeeeeeeeeeeeeeep" to be a particularly valid criterion when selecting car parts. Just because somebody didn't go to jail for wire or postal fraud for printing the word "[fill in the blank]" on the box they put their ultimately crappy thing in, doesn't mean I want it.

Of course that doesn't automatically mean, go spend the most money you possibly can, either. There's always a question of "value"; bang for the buck if you will. But the truest truism in all of commerce is, that you get, AT BEST, what you pay for; meaning, if you deliberately pay THE LEAST, then you get, AT BEST, ... I'll let you finish the math.

That said, a good brand for not too much $$$, that fits and mostly sounds like OEM, is Dynomax (Walker).

 

That's all I'm looking for, just your all's opinion on what you would get if you were replacing a stock system with cost at least in mind.

 

Summit and Jets both sell their own systems or many other brands. I'd get a 3in system.

 

 

K, so will the dynomax look like a stock system? RockAuto a good place to get one?
I'm completely new to working on old cars if you can't tell.

 

dynomax/walker is probably as close as you can get to stock. RA has provided the best price on several walker systems for me in the past. make sure you get the one for a TPI.

if you can wait a bit, walker/dynomax usually has a rebate in the Spring.

 

So the Walker 17493 would work with an 88 iroc 305?

 

If Walker lists it for 88 Camaro 305, it'll work in your car.

Might be different for TBI vs TPI, as naf hinted at. If you have TBI, and that's for TBI, DON'T spend a dime on it. Instead, find somebody that's taking off their TPI manifolds & Y-pipe, and put those on your car instead; and get the TPI cat & cat-back to match. Otherwise you're just spending a whole wad of cash to perpetuate the bottleneck that's the primary malfunction keeping your TBI car slow.

 

Keep in mind that most if not all of these cat backs have 2.5" intermediate pipes.

All LB9s until 1990, (non-N10), all L98s and all L69s had 2.75" IPs from the factory.

You'll get a boost if your car came originally with the 2" exhaust manifolds and 2.25" IP. You'll lose a few ponies if your car came with 2.25" exhaust manifolds and 2.75" IP.

 

Precisely. Good detailing of the sizes on the various models, and pretty obvious why, if you have a L03, you DO NOT want to go spend $$100s$$ on retaining the same drinking-straw-sized choke job.

Some of the other popular cat-backs, Hooker for example, use a 3" I-pipe. But it doesn't sound all that much like OEM. Not "bad", not particularly "loud" at idle, but when you stand on the skinny pedal, it's quite a bit louder than stock. As I would suspect all of the ones with the larger I-pipes will tend to be... more often than not, people buying in that direction, aren't looking for "stock sound".

 

the TPI kit I installed several years ago had a 2.75" I pipe and 2.75" connection to the stock size cat BUT necked down to 2.5" at connection to muffler. It was a Walker but I don't have a record of the part number although it should be the same one.

A true 3" I pipe kit can be fabricated from the Walker I pipe for a 4th gen BUT will not fit a stock cat for a third gen. Slip fit vs two-bolt, diameter 'may' be an issue as well.

 

I wish I knew that.

When the cat on my '85 exploded, ( secondary to previous damage from the previous owner), and peppered my I pipe with platinum shrapnel, I searched everywhere for a commercially available piece, but all of them were 2.5". In the end I had one made at an exhaust shop.