Hi guys. I am swapping an L92 Escalade engine into my car. Its basically turned into an LS3 now tho minus the hollow valve's. Has beehive dual springs and a cam with .660 ish lift and lots of duration. Not sure the exact numbers at the moment. Its a one off custom grind from Comp Cams.
Anyhow. What kind of exhaust should i run?
I have a set of LS1 Camaro Manifolds that i got for free. Was considering running those for the time for a money saver. But wouldnt they be restrictive? What kinda HP/TQ numbers can i expect switching from the Manifolds to long tube headers?

I was also looking at the SLP Loudmouth exhaust from the LS1 car's and modifing it to fit mine. Would the 3" single be suffiecient enough?
I am gonna be lowering my car a little bit so ground clearance maybe an issue with a 4" system, and i dont see how to run 2.5" duals out the back and over the axle without a ton of custom work.

 

With a cam that big, really everything off the shelf isng going to be up to par.

The minimum i'd choose for that would be hawks 1-7/8 headers, then dual 3" into single 3.5, preferribly the single 4"

 

So your saying that the LS1 manifolds are gonna restrict it a ton than and rob me of quite a bit of power?
I wanted to go with the SLP kit as i like the Loudmouth. I've never heard a Loudmouth Resonator before in person, but they sound good on youtube.

I want it loud, like not absolute retarded open header loud, but i like loud.
Might consider electric cut outs even just to have.


We also have a 77 T/A with a Buick 455 (completely done up, about 600hp) with 2.5" Duals, Flowmaster 40's and long tube headers (cant remember size) and its got such a nice sound and tone to it. I want it loud like that car but a nice modern day loud muscle car sound.

 

LSx manifolds are restrictive compared to headers, especially larger long tubes, but compared to manifolds of older engines, they flow extremely well

4th gens usually report 15-20hp gain switching from manifolds to long tubes

Next, 3" catbacks like LM1/2 are very capable. Lots of 4th gens run 350-500hp on a single 3". Would a larger exhaust free up a little? Sure, but it doesnt seem like you're scraping in every last bit of power, so an off the shelf system thats known to fit would be right up your alley

Check out the LM1 system. Its loud as the name implies and doesnt sound too bad. The down side is it has a drone at a particular RPM, usually around 2000. To fix this, install a cat

 

Thanks Pocket. Whats needed to make a LM1 system from an LS1 car work on my 91?
I am thinking either Hawk's headers or Hedman Swap Header's. Both can be bought with 1 7/8 primaries. But the Hedman's are a little cheaper.
Anyone ever run the Hedman's yet?


And im not conserded about droning or being loud. I want it to be loud. The car see's maybe 500-1000 miles a summer and thats it. So i dont care about drone.

 

Change a few hangar locations and any 4th gen cat-back exhaust will work in a 3rd gen

There is a thread about the hedman mids in a swap in the LTx/LSx section