My 91 LO3 had a nice but subtle sound so I figured I'd take a look at the exhaust. To my amazement it was factory Y, factory cat, 2 1/4" cat back straight pipes. Well it's more a chambered exhaust setup without the chambers.

I was going to gut the cat but with this setup I might as well make reservations on the tickets that I'll get.

My thought is that the cat is more restrictive than a free flowing muffler. Would I be better off leaving as is or gut the cat and go with a flowmaster delta flow series or a ravin etc.

Again daily driver so not wanting max power just better throttle, better mpg's and a nice exhaust note.

 

Without a muffler it's going to be loud. Get a high flow cat and a high flow muffler, it will be better for the environment and it will sound good without the popping of a gutted cat. High flow cats are nearly as good as straight pipes... and they're legal. You're not likely to see a difference in mileage until you've got headers, y-pipe and a full catback.

 

Not that you make the power of my stock LT1 but here is a clip of my 95 Z with a gutted cat and no muffler, i love it...

 

there's no muffler on it now and it isn't loud, kinda snarely. Without the cat it would be. I have no kinda emissions test beyond the bend down look yep it's on there.

Not to start an argument but none of these cars are good for the environment, I don't care what's on em.

Nope lo3 is nowhere close to lt1 in power, probably lacking from a 3800 bone stock, but it's a nice daily driver. I have a 383 on the engine stand begging for a home. I was gonna stick in a 87 sport coupe car but I bought this one dirt cheap and hey it saves time, money and work so why not.

I owned a 95 Z28 it was alright and handled like a dream but the 383 is out of my 79 and the lt1 (bone stock beyond flowmaster and k and n) could barely keep up until I ran out of gears. 3 speed auto vs. 6 speed

 

The environmental issue is just a side note, I've had a gutted cat before and it sounds kinda crappy on deceleration... I've also run with just a y-pipe and it was unbearable at anything above idle, but my definition of loud is probably much different than yours, personally I wouldn't straight pipe a daily driver, though it will be quieter in the cabin than just a y-pipe or uncapped LT's.

 

Holy hell dude, that must draw some unwanted attention from the police.

 

im thinking the tbi cats where very restrictive as i ran mine with no muffler for a bit car
it really wasnt overly loud it was quiter then most cars with proformance mufflers

i put a flowmaster on it and its not even as loud as the factory muffler but its also a 30 series from force 2 setup but the car seems like it has more pep then it did with no muffler mainly it will chirp 2nd now but it didnt do it with no muffler
who knows lol

 

I'm thinking gutted cat and deltaflow series from flowmaster. Anybody run a ravin on here? Sounds great on trucks, well that 305 tbi belongs in a truck so it'd probably pan out.

Here goes probably world war 33 but the lo3's are choked way down and before I would spend the money to get it to perform I'd go to a 350 where it would be more beneficial for MY needs/pocketbooks. But the guys on here that pump out power from their lo3's more power to em. At least somebody acknoledges their is potential in em ever so slightly but it's there. Just tryin to keep peace.

 

with cat, no muffler
http://vids.myspace.com/index.cfm?fu...oid=1693773093

with cat and force proseries muffler
http://vids.myspace.com/index.cfm?fu...oID=2012117019

 

so far what ive noticed with mine is that there is potential there but only so much the l03 are far to restricted from intake to exhaust to haveing a peanut cam and fpr set very low to also haveing crap gears

when gm came out with the lo3 in the camaro it was in no means ment for proformace

if you fix the inherint flaws gm gave it
you gain alot compared to stock but in todays world you still end up with the speed of most v6 sedans

 

You keep your car long enough and you will have more than the "bend down and Yep it is there" type of inspection.

Nowadays they make the cat's very efficient and free flowing so it makes sense to leave it in place (you have many muffer options). If you disconnect the AIR line and decide to leave the cat in place, make sure to get a 2 way cat.

BTW, My 355 (with headers) ran with a 3" gutted cat welded into place with a single in/out flowmaster 3". The engine makes around 350 HP and it sounds like the Sunday morning choir when you hit it (even at half throttle).

 

As long as i am driving "normal" it is ok. But WOT or even playing slightly it turns allot of heads.

 

true true the lo3 cats are VERY restrictive and after time pack up with SHI*. after owning my car and new the means of a 305, it just didnt seem right to beable to cruise at 4000rpm in forth and hardly climb a steep hill, cut the cat cut the muffler welded straight duals off exsisting rear pipe, LOud As HeLL but gained power! LOTS

 

i have headers, no cat, 80 series flowmaster. Im not that loud..Im changing the muffler to a dynomax and getting rid of the dual out muffler for better exhaust flow and more power.