Question about exhaust tail pipe size.
 

I’m redoing the exhaust on the ’88 k2500. When I got the truck, the pipe exited in front of the rear tire. I want to bring in out rear of the rear tire. The pipe is 3” from the y-pipe to the cat, and to the muffler with the old exit being 3”.

When I search on-line for this specific vehicle I’m seeing a 2-1/4” pipe with 3” inlet. Why? Should I get the 2-1/4” pipe with 3” inlet, or get a 3” pipe? How was it from the factory? I saw a couple trucks in the scrapyard that had the 2-1/4” pipe, or dual mufflers, but no 3” tail pipe.

Re: Question about exhaust tail pipe size.
 

Dual 2.25 was factory, someone has changed it on your truck. Just keep with the single 3" like it is already, works perfect.

Re: Question about exhaust tail pipe size.
 

I like your reply, maybe I’m putting too much thought into this.
I noticed the exhaust on my ’90 k1500 is single 3” pipe. I’m wondering if the 4x4’s had single and the 2wd had dual. There is a front diff drop and fuel tank on the driver side of the 4x4, so no room for dual there, or would they have gone down the passenger side? How are they routed on the 2wd? I found an article comparing the two sizes. It showed more torque and HP at lower rpm with the 2.25”, and more torque and HP at higher rpm with the 3”. The difference was 1, so not much. I would like a quieter ride, my ’90 k1500 is loud. I would consider going with 2.25 for a tamer sound. Yesterday I happened to pull up behind a truck of this era with one exhaust tailpipe, not 3” from what I could see. It was a nice truck, looked good. After driving a few blocks and hearing it, it sounded anemic, nasaly. I’ll go with the 3” and get what I get sound-wise.

Re: Question about exhaust tail pipe size.
 

if i recall, the 2x4 was a dual exit, the 4x4 was single ( generally see the Z71 with a single pipe)...but i also recall that being a model year item also

honestly, it is probably more your preference...i am currently re fabbing mine from header back, going to go with a true 2.5" pipe through the muffler area... (solid 400 hp small block)
then seeing what i can truly do with a 4 link and rear cantilever, the pan hard bar and rear cantilever travels eats a lot of possibilities

Re: Question about exhaust tail pipe size.
 

I did not know that duals came on these from the factory. All of mine (all 2WD - a 92, 2 94s, and a 96) were single exhaust, that got converted to duals in a cat back setup. I would say for the 4x4 a single 3" would be a better option, regardless.

Re: Question about exhaust tail pipe size.
 

The earlier years of these trucks ran a "dual tailpipe" exhaust. They were all 3" after the y-pipes, as far as I know, then the dual tailpipes used a 1 into 2 muffler. I don't know the diameter of the dual tailpipes. Tom said 2.25". I run a 1 into 2 muffler (3" in/2 1/4" out) with dual 2 1/4" tailpipes on my '95 Suburban

Re: Question about exhaust tail pipe size.
 

I just remembered, starting in 96 they changed the front half of the exhaust. Instead of a single into the muffler, they had a dual into the muffler (and single out). I believe the Vortecs used dual cats, so when you converted the tail pipe area you went to a dual in dual out muffler. I believe they were 2.5" on the Vortec, but may have been 2.25. I know this does not apply to your 88, but just something I remembered about them.

Re: Question about exhaust tail pipe size.
 

My 98 stock had dual 2.25 each with its own cat that go into the same muffler, then a single pipe exiting the muffler going over the axle and exiting in the rear. I put a flowmaster 50 series on buy cutting off the stock muffler and welding it onto the oem pipes with a single 3" outlet that just has a dump welded on.

Re: Question about exhaust tail pipe size.
 

That's good to know. So I guess it was with the Vortec they went dual to the muffler, which was '96.

The dual tailpipes I had run on my '95 rotted off and the muffler is looking rough so I'm looking to do something with my exhaust, too. What I really want to do is run true dual pipes all the way, because you still can on these Suburbans.