Need to get rid of the exhaust RASP!
TECH Fanatic
Joined: Nov 2001
Posts: 1,098
Likes: 0
From: I-L-L-I-N-O-I-S
Originally Posted by WS6Power
I had the same problem with rasp at around 2500 rpms. It`s just the nature of the LS1, it may have something to do with the firing order. Don`t add cats to your car unless you want to lose 15 HP. I added a dynomax bullet in the I-pipe, it`s the cheapest cure. Or you could ditch the Corsa and add the Hooker cat-back for around $300. It flows good and sounds great. Check out the sound clips above.
Unless this is regarding some stock cats or generic Catco's, you obviously don't know what you're talking about...Anyways, I absolutely do NOT like the sound of catless Y-pipe set-ups on 4th gens at all...The rasp sounds like **** in the mid rpms and the lack of cats do not provide a good tone IMO...I actually have a 12" Dynomax Bullet in place of the cat on my LT1 and I am not happy with the sound of the car anymore, so I'm having a Random Tech highflow welded in place of it next week. With the offroad pipe, it would sound even worse.
Like said, the bullet will help, but only a little as you'll still have noticeable rasp. But if you want to kill it completely and have a deeper/cleaner tone, go with a catted Y.
Or true duals with an X-pipe set-up if you decide you must leave the cats off...Mike
Like said, the bullet will help, but only a little as you'll still have noticeable rasp. But if you want to kill it completely and have a deeper/cleaner tone, go with a catted Y.
Mike this is why I went with the Sprial flow bullet. On a scale of 100, with 1 being the worst. It took care of 99% of the rasp. It also toned the car down enough that I can drive around the city with any fear of getting a ticket. Before anything over 2,000 rpm was loud enough that you will get a ticket.
Now a LT/MId header with a gmmg and no cats is go to jail loud. It was fun for about 2 wks!! If somebody says it isnt loud they have severe hearing Loss!!!
Later John 
I believe the guys that lost big HP using the CCI inserts were just putting one in the i-pipe, not one in each side of the y-pipe like I did. It makes a big differance which direction you install them also. I did not feel like there was a drop in HP. If you put just a single one in the i-pipe it does not kill the rasp like one in each side of the y-pipe.
Thread Starter
Launching!
Joined: Mar 2005
Posts: 216
Likes: 0
From: Elgin,IL
Wow! This is bunch of info to digest! I like loud but as someone once said, sorry I missed that my car is too loud, what did you say! My car is very loud, which I like but I dont think the local cops will like it too long. Is the spiral flow mentioned above made by moroso or is there another available? I might be better off with a couple of cats in the Y to quiet her down a little. Now here is the $2 question what cats to go with!?!?
Originally Posted by TOOSLO5
Wow! This is bunch of info to digest! I like loud but as someone once said, sorry I missed that my car is too loud, what did you say! My car is very loud, which I like but I dont think the local cops will like it too long. Is the spiral flow mentioned above made by moroso or is there another available? I might be better off with a couple of cats in the Y to quiet her down a little. Now here is the $2 question what cats to go with!?!?
Thread Starter
Launching!
Joined: Mar 2005
Posts: 216
Likes: 0
From: Elgin,IL
Thanks for the info. I found their web site and it looks like the F4 is 4" od and comes in two lenghts, 12" and 17" bodies. I like the idea of the Flo Pro and the install could be done easily. I will be sure to post what I do and the results after I make up my mind, whenever that may be.
