3" cat-back exhuast

[Jeff7]

Hey guys,

I'm looking for some advice on an exhaust modification. I have a 98 K1500 with the 5.7L. I found a guy who is parting out a truck and it has 3" exhaust all the way from the headers (no cats) into 2 magnaflow mufflers. I want to keep my cats but I'm thinking if I buy this setup off of him I could cut it and weld the 3" pipes to that flange just after the cats. Right now I'm pretty sure my exhaust is the 1 7/8" pipe, what are your thoughts on the size change? Would this have a negative effect on my system or since it's far enough back would it not matter? I'm new to this so I would be getting someone else to do it, I just want to know if it's worth buying the exhaust or not. Any advice is helpful.

Thanks,

Jeff

 

[GMC1994K1500SierraSL]

So it has two 3" pipes? And two mufflers?


Sent from my iPhone using Tapatalk

 

[Jeff7]

Ya the one I'm looking at buying is 3" true duals, so pipe from headers to 2 separate 3" in / 3" out mufflers and then the piping to either side of the truck out the back.

 

[GMRedline]

3" True duels is extreme over kill for your engine unless you are pushing 1000hp. Your low end is going to be terrible.

 

[Jeff7]

Even with stock headers and cats?

 

[Jeff7]

What if I only used one pipe? Put a Y pipe after the cats and have only one 3" pipe/muffler going out the back?

 

[GMRedline]

Even with stock headers and cats?

Yes

In "General"

You must be registered for see images attach

What if I only used one pipe? Put a Y pipe after the cats and have only one 3" pipe/muffler going out the back?

That would be a better choice. There are some relatively inexpensive options out there.

Check out some of these resent threads.

http://www.gmt400.com/forum/showthr...-for-a-Bolt-on-Y-pipe-upgrade-for-a-96-vortec

http://www.gmt400.com/forum/showthr...Pipe-on-a-Vortec-3%94-SI-SO-Exhaust-for-Burbs

 

[Jeff7]

Yea I've seen that chart before, thanks for finding it again though. I just figured that keeping it stock further up would be a bottle neck, and so the cat-back portion wouldn't matter as much. Poor assumption I guess haha.

 

[Jeff7]

Yea those threads are pretty helpful, thanks. I was hoping to have the looks of 2 tail pipes but whatever. So when I was considering doing full duals I was thinking about putting in an H pipe too. But now if I'm going to put a Y pipe after the cats into one muffler putting an H pipe between the cats and the Y pipe would be pretty pointless eh?

 

[Nathaniel2g]

I've got stock headers and stock cats. They should all be 2 3/4" from factory. Custom fabbed an H pipe to go from the cat flange (welded on, burnt 2 gaskets out before I was smart enough for this) to the Magnaflow XL series dual in-single out muffler. I can get a video and post it up if you'd like?