Ive got pacesetter shorties and the then 2.25" true duals no xpipe running out to some summit street/strip cheapo mufflers.

Is 2.25" pipe too small?

truck only has the small xr259hr cam in it.

also want something to really make the cam stand out at idle muffler wise...any opinions? Spintech(if so which one) magnaflows? flowbasterds?

thanks

 

Everybody will tell you to sell the shorties and go with longtubes.... so there's that lol

I had shorties with 2.25" true dual with supper 40 dual in/out put probably got the best mpgs and power bellow 2000 rpms with this set up. Then I switched to what is in my sig.

I gained 14rwhp and an average of 8rwtq with a peak of 11rwtq gains from the LT and 2.5" with xpipe.

I would say get a muffler that you really like the sound of, and then throw some cut-outs on for when you want it obnoxious, that's how mine is set up and I love it. If I'm cursing around town cut-outs open for highway drives close them b****es up haha

 

the stock manifolds are as good as shortys. go 2 1/2 inch with no cats.

 

^ yup if you can sell the shorties and get long tubes I would do that, but you will need a tune to see the full potential from them. I would run 2.5". 2.25" is to small and 3" is to large for a little 5.3L.

If you have to keep the cats for emissions purposes then I would invest in some high flow cats, I bought mine for $70ish a piece from Advanced autoparts or some online place like that.

 

its in a 68 c10, and the only thing close to longtubes made for this swap is doug thorleys mid length headers and they're too pricey for the small gain they would give.

no cats and keeping the 2.25 since its true duals no real need for larger from what Ive been reading on LS1tech.

I bought me some super 44s that will go on tonight.

 

awhhh 68 c10 that makes sense on your header decision. Yea there wouldn't really be much difference between 2.25 and 2.5", but 3" you would lose some low end tq.

Plus a lot of guy are making well over 400 hp with a y pipe 3" tube. Flow masters sound good, I just can't stand the drone they have for my dd that is. I can live with drone in a toy.

 

I am in the same boat for the most part with my K10 in regards to long tubes. It's funny, I always thought you C10 guys got all the love in this market lol. My plan is to buy the cheapest set of f-body headers from ebay, so I dont feel bad when I have to "message" them into place. I'm not sure how different the clearances are in yours, but here is a pic of my engine bay.
(Crappy cell phone pics)





The engine still needs to be moved forward about 2" but I do believe the 4th gen f-body headers will only need minor work to to make them fit. I have also read that the 5th gen headers offer better clearance but nothing confirming this. Sorry this got a little off topic OP.

 

montecarloss has tried a few headers on his 86. he can probably tell you what fits best.

 

a quick search says f-body headers should fit with no mods
https://www.performancetrucks.net/fo...ot-fit-457697/

 

My 04 GTO came stock with 2.25" duals. A Magnaflow 2.5"catback only gained 5 hp. This was with a 5.7 LS1. With a 5.3, you'll be fine.