Generation III External Engine - Removinng the Rasp?

I'm going to be seeing an LS1 expert this week, but I'd still like to still see what anyone thinks about my predicament. I have a 2000 WS6 Trans am with Flowtech long tube headers, Off-road Y Pipe, and straight pipe (SLP Loudmouth w/o the resonator) the rest of the way back...no cats, resonators, mufflers...nothing. I like the volume and overall tone, but as is apparently common for these cars, the rasp that comes just before the shift is terrible. Does anyone have any suggestions as to how I can eliminate the rasp as much as possible without turning the overall volume way down?

by the way...I heard once that adding a high-flow cat would reduce the rasp significantly....i was thinking about putting one of these on the straight pipe...thoughts?
http://www.ebay.com/itm/3-Magnaflow-Universal-59959-Catalytic-Converter-High-Flow-Spun-Metallic-Cat-/110847989857?pt=Motors_Car_Truck_Parts_Accessories&hash=item19cf0e1861&vxp=mtr

The y-pipe is what causes the rasp. So your best bet is to either try the cat in the I pipe or run a muffler again. I had basically the same set up and hated the rasp. Now I took all that out and put true duals on. Sounds amazing. I have 2 high frlow cats an x-pipe and 2 dynomax bullet mufflers.

The y-pipe is what causes the rasp. So your best bet is to either try the cat in the I pipe or run a muffler again. I had basically the same set up and hated the rasp. Now I took all that out and put true duals on. Sounds amazing. I have 2 high frlow cats an x-pipe and 2 dynomax bullet mufflers.

well...since i dont have the budget for all of that...you would suggest the cat i was thinking about or a bullet muffler on the straight pipe? which do you think would reduce the rasp more and maintain a good tone for the exhaust over all

I have BBK LTs and the 3" off road Y pipe mated to a SLP LM1 with the bullet muffler still attached. Its raspy as a bastard......


strangely enough I remember test driving the car, after the install, with the LTs bolted to the ORY and it wasnt as raspy... Leads me to believe its something to do with the cat back set up, hmmm

I had a bullet muffler put in my I-pipe and like Mattyfresh89 said it didn't do shit. The flow through design doesnt do much. I would go with a single cat like you have there or maybe one on each side like a typical set up.
Check these guys out too: http://performance-curve.com/

I had a bullet muffler put in my I-pipe and like Mattyfresh89 said it didn't do shit. The flow through design doesnt do much. I would go with a single cat like you have there or maybe one on each side like a typical set up.
Check these guys out too: http://performance-curve.com/

thanks for the info. im leaning toward the cat anyway...do you think itll kill the overall volume too much?

thanks for the info. im leaning toward the cat anyway...do you think itll kill the overall volume too much?

doubtful, it will obviously take some volume away.

Only example I have is my buddys gto, although its LS2, full exhaust with a high flow cat ==> SOUNDS AWESOME! (true dual though, x pipe to Corssa)

I've heard other gto's with a similar set up with "fake cats" or no cats and they dont sound as tight

Yea you may loose a little tone but like Mattyfresh89 it'll probably tighten it up and let you hear the exhaust. not the rasp.

doubtful, it will obviously take some volume away.

Only example I have is my buddys gto, although its LS2, full exhaust with a high flow cat ==> SOUNDS AWESOME! (true dual though, x pipe to Corssa)

I've heard other gto's with a similar set up with "fake cats" or no cats and they dont sound as tight

alrighty...i know ill lose some sound...but as long as the rasp is reduced more than the the rest ill be ok lol. the link you gave me above...do you recommend them from personal experience or just because its cheap and appears to be good? ive used magnaflow cats before and was very pleased so im inclined to go with that one...unless you have info to the contrary.

im not a total noob when it comes to exhaust...just this whole rasp situation lol.

alrighty...i know ill lose some sound...but as long as the rasp is reduced more than the the rest ill be ok lol. the link you gave me above...do you recommend them from personal experience or just because its cheap and appears to be good? ive used magnaflow cats before and was very pleased so im inclined to go with that one...unless you have info to the contrary.

im not a total noob when it comes to exhaust...just this whole rasp situation lol.

i was referring to the link from 01ta...not matty. sorry for the confusion

you remove rasp by removing the y pipe, lm1 is the worst exhaust for a modded car, honest i have had alot of catbacks , they dont even compare to a good dual setup

you remove rasp by removing the y pipe, lm1 is the worst exhaust for a modded car, honest i have had alot of catbacks , they dont even compare to a good dual setup

well...my brother has a camaro with the lm1 setup but he has the "muffler" and the cats and his sounds perfect. since the muffler isnt super impactful...im thinking the cat should make enough of a difference....besides, at this point...im not running an slp kit...its just 3 inch pipe everywhere except the tail pipes

I have experience with them. Great bang for the buck. I live in colorado and still have emissions and they still allow me to pass even being high-flow. I have one on each side off my headers.

I have experience with them. Great bang for the buck. I live in colorado and still have emissions and they still allow me to pass even being high-flow. I have one on each side off my headers.

cool..you dont have to have experience with the magnaflow too do you? that would be perfect hahaha. which model did you use?

No no experience with magnaflow lol sorry.
http://performance-curve.com/2goerlichcatalyticconverterobdii608214-1-1-1.aspx

mine are about 2 years old so not the stainless versions but same design.

No no experience with magnaflow lol sorry.
http://performance-curve.com/2goerlichcatalyticconverterobdii608214-1-1-1.aspx

mine are about 2 years old so not the stainless versions but same design.

sweet. thanks a lot. do you have a pic of where you placed them in the system?

What type of ORY do you have?

<a href="http://s1050.photobucket.com/albums/s412/01transampower/?action=view&amp;current=101_1115.jpg" target="_blank"><img src="http://i1050.photobucket.com/albums/s412/01transampower/101_1115.jpg" border="0" alt="Photobucket"></a>

Now with my Poly motor mounts and my Jet Hot headers my driver side header sits close to the floor pan so the cat had to be moved back further in the system but still serves its purpose. As you can see the passenger side is fine. Most of the time it sould fit right after the collector.

http://i1050.photobucket.com/albums/s412/01transampower/101_1115.jpg

What type of ORY do you have?

no clue..it was there when i got the car

http://i1050.photobucket.com/albums/s412/01transampower/101_1115.jpg

i have flanges where your cats are. maybe ill just cut them out and weld the cats right in place like you did.

no clue..it was there when i got the car

a $40 flow master y merge eliminates rasp from what i hear and its a GREAT looking merge. Take a pic of your ORY maybe someone can tell you what brand Y it is.

That would work good since you already got flanges. I wanted flanges but no room with the driver side header so close to the floor. But it should work great for you.

That would work good since you already got flanges. I wanted flanges but no room with the driver side header so close to the floor. But it should work great for you.

well i was thinking about just replacing the flanges with the cats since the cats would need to have flanges weld on to be used anyway

True. very tue.

True. very tue.

i figure that everything else is welded so why not go for the whole shebang.

yea exhaust leaks suck. thats why all of mine is welded too. the only place it not is the slip fit on the header collectors and the flanges on the back where th pipes run under the axel and out the back.

yea exhaust leaks suck. thats why all of mine is welded too. the only place it not is the slip fit on the header collectors and the flanges on the back where th pipes run under the axel and out the back.

its funny you say that. my brother and i were just talkign and decided it would be best to use a slip clamp on the headers end of the new cats and just weld them on to the y-pipe. i just hope there is room enough in front of the o2 sensors on the y. i wish i could get a pic of it...or even look under there right now so i could do some measuring. damn low cars

See i deleted my rear 02's and only have the fronts. You should be able to see taht in the picture. You should be ok using the slip fit style.

See i deleted my rear 02's and only have the fronts. You should be able to see taht in the picture. You should be ok using the slip fit style.

tbh...i dont remember whats down there on my car. i didnt do that part of the exhaust so ill have to check. i think i have it like yours though

If you have them and keep them then i would but if you have to pul the back o2's dont worry they dont do anyhting anyway. they make sims to foo the computer they're there or you can get them tuned out. If you have them if not it'll be all the more asier lol.

i use to have thunder bolt cats on my lm1 with long tubes. there was no rasp at all. i now have an ory and there is some rasp but its much louder. pick ur poision lol

If you have them and keep them then i would but if you have to pul the back o2's dont worry they dont do anyhting anyway. they make sims to foo the computer they're there or you can get them tuned out. If you have them if not it'll be all the more asier lol.

well, unless there is a batch of them up pretty high on the headers, i only have the one set...on the headers' collector i believe

i use to have thunder bolt cats on my lm1 with long tubes. there was no rasp at all. i now have an ory and there is some rasp but its much louder. pick ur poision lol

so what youre saying is that with my longtube headers, ory, straight 3 inch pipe to the 2.5 in tailpipes...with a set of thunderbolt cats after the headers, itll sound nice and loud/good with a just a bit of rasp?

so what youre saying is that with my longtube headers, ory, straight 3 inch pipe to the 2.5 in tailpipes...with a set of thunderbolt cats after the headers, itll sound nice and loud/good with a just a bit of rasp?

The cats will kill all the poping and rasp if thats what you dont like.

The cats will kill all the poping and rasp if thats what you dont like.

thats the plan. what are your thoughts on how much the thunderbolt cats will effect the overall volume though?

well, unless there is a batch of them up pretty high on the headers, i only have the one set...on the headers' collector i believe

Your rear o2's have been deleted then already so no need to worry about them then.