the monte ls4 is actually getting more options for the exhaust. you could go mild or wild:

--doug thorley headers with a catback exhaust of your choice
--a 3" hogan downpipe into a 2.5" catback exhaust
--a catback exhaust kit (magnaflow makes a great stainless kit) or custom setup done by a shop
--you could simply have the two stock mufflers replaced with the muffler of your choice, pretty sure this is what rickakated10 did. great sound for economical price.

i prefer the sound of magnaflows the best, but it's up to you. go with 2.5" pipe, 3" is too big for that engine IMO

 

Definitely not too loud. I like it more now than I did when it was first installed.

 

im prob going to do a hogan catted downpipe with a custom cat back

 

i dont think 3 inch is too big but its not necessary dont for get its a single exhaust not a true dual. you could always leave the factory resonator on and remove the mufflers completely and run straight pipe out the back. its not as insanely loud as you would think. heres mine from a previous thread.
https://montecarloforum.com/forum/sh...ad.php?t=16312

 

ive noticed that most of you guys are running three inch pipes all the way back to flowmaster 44's. I dont even have three inches on my 455 cutlass only 2.5..............On my last monte i had 2 1/4 all the way back to the flowmasters and it sounded really nice........u think i should go bigger like 2.5 or 3?

 

i did dual flowmaster 40 series muffles with no resonater and it sounds really deep with my 3.5 monte...pics and vids will be up soon on my page

 

im also confused.......exactly what is a ls4 monte?

 

old thread but i saw it and figured id answer your question either way. ls4 is an engine designation for the 06/07 fwd 5.3 v8 in the MCSS(IMPSS,LAXsuper,GPGXP). they only ade 40,000 or so of all the different makes combined. its shrunken down ls2 turned sideways with ls6 heads. and to answer your exhaust question, on my 80 im running 2.5" with no cats from the headers back with flowmaster 40s. i dont feel 3" is truly necessary unless your making big power. close to 600hp. 500 and under the power gain is probably miniscule and doesnt warrant the 3" in my opinion.