KC_kid

iTrader: (5)

Stock 5.3, probably a small cam someday but currently is stock. I have Doug Thorley tri-y headers to put on, they have 1-5/8" primaries. I have been offered a free 6.2 catback, thinking of taking it.

Question - Any reason to worry about the smaller primary header going into the 3.5" catback? I'm wondering about high velocity exhaust slowing down quickly in the bigger tube, causing unwanted back pressure... or am I over thinking this?

Is the stock 6.2 catback good system for a 5.3 with tri-y's?
Thanks

JordanH

iTrader: (16)

You're over thinking it... The 6.2 cat back will be perfectly fine! Those motors(6.2) flow a lot more than our 5.3's do!

KC_kid

iTrader: (5)

I just didn't want to oversize it and lose low end. My goals are to keep as much low end as possible, which is why I chose the smaller primary try-y headers.

53bowtie

iTrader: (6)

You could definitely get away with a 3" exhaust but I don't think you will lose much going with the 3.5" with the stock muffler.

I am running 1 3/4" headers with Y-pipe-back 6.2L factory exhaust on my Lq9 and love it. Perfect idle sound but gets pretty rowdy when you step on it.

KC_kid

iTrader: (5)

Thanks for the response. I tend to over analyze things...

Fast355

You are definately over analyzing it. My stock 5.7 exhaust bumped up to dual 3" about 2" after the exhaust manifold flanges and ran into dual 3" cats and then into a dual 3" in single 2.75" out muffler. My Thorleys were designed to mate up with the 3" pipes right after the 2.5" collectors. The 350 woke up noticeably everywhere after headers went on. I brought the pipe smoothly down from 3" to 2.75" mandrel bends to 2.5" at the cats, 2.5" into a dual in/single out walker dynomax school bus muffler with a 3" tailpipe.