2.5” exhaust kit for 85 suburban?

[txaggie]

Howdy all!

Does anyone know of a 2.5” full dual kit for a suburban? All I can find is 2.25”.

 

[TotalyHucked]

There are very few “kits” for these trucks. I’ve always just gone to the muffler shop and had a whole system bent up. Works out to be roughly the same cost usually and much better fitment

 

[75gmck25]

There are many 2 1/4” kits, so they are reasonably priced and easy to find. There is only one off the shelf 2 1/2” kit for 2WD vehicles that I’ve seen, and I think the brand was Pypes. It was at least double the price of the 2 1/4” kits, but it was also higher quality tubing.
How deep are your pockets?

https://www.classicindustries.com/product/1975/gmc/truck/parts/p1012.html

 

[txaggie]

my friend actually found one online for me:

https://www.partsgeek.com/jnrpc9n-chevrolet-k20-suburban-exhaust-system.html

 

[bucket]

my friend actually found one online for me:

https://www.partsgeek.com/jnrpc9n-chevrolet-k20-suburban-exhaust-system.html

Without cross referencing part numbers, I can just about guarantee that's a listing error. It should be 2.25" pipes and besides that, they are crush bent and not mandrel bent.

Besides Pypes, Hooker also used to offer a 2.5" kit. Iirc, it was the "Super Competition" line. They also had a 2.25" kit that was much cheaper.

 

[txaggie]

Without cross referencing part numbers, I can just about guarantee that's a listing error. It should be 2.25" pipes and besides that, they are crush bent and not mandrel bent.

Besides Pypes, Hooker also used to offer a 2.5" kit. Iirc, it was the "Super Competition" line. They also had a 2.25" kit that was much cheaper.

Ugh, maybe I just run with this kit anyway? I wonder how much a difference 2 1/4 over 2 1/2 will be?

 

[75gmck25]

If you have a relatively stock vintage 454, slightly smaller exhaust will not make much difference. Just make sure you get good flowing mufflers and an H or X pipe so you make the best out of 2 1/4” exhaust.

There are flow limits in the older heads, limits to stock iron intakes, low compression, and many other suboptimal features of a stock engine. A little better exhaust won’t solve those problems. Now if you already had high performance heads and intake, high compression, high performance cam, and large tube headers, then the smaller exhaust might be a limiting factor.

 

[txaggie]

Thanks! In the next 6-12 months, heads, fuel injection, and cam will commence. I might as well put the right exhaust on for that now I’m guessing.

 

[bucket]

Ugh, maybe I just run with this kit anyway? I wonder how much a difference 2 1/4 over 2 1/2 will be?

Probably not that noticeable for the average fella. The crush bends definitely don't help though.

 

[CalSgt]

If you’re willing to do some welding and spend the time to fit everything this Flowmaster kit is a decent option, looks like the price has gone up a little since I did mine (I did same kit but in 2.25).

The only thing it didn’t have was the mufflers, flanged connectors for manifolds, and I bought one “U” bend to cut up so I could get the fit just perfect. I could have done without the u bend if I didn’t have to sweep the pipe away from the frame mounted fuel filter.

You must be registered for see images attach

You must be registered for see images attach

Here’s the U bend cuts I was talking about.

You must be registered for see images attach

 

[peats]

You can buy the 2 1/2" pipes pre bent for over the axle and out the side on the net. I would suggest a local muffler shop for the engine to the mufflers. Don't waste your time or money on a crossover or H pipe, they produce minimal performance gains.