wrd1972

I currently have LPP long tube headers and a Borla adjustable catback. I just recently removed my two mini-cats from my Y-pipe and am noticing a strange sound coming from under the car in the 2500 - 4000 RPM range when under load. Again what I am hearing is coming from under the car.

Its a light rattling almost raspy sound and it must be exhaust pipe related I never heard this sound when the cats were on and nothing else has been changed. I have been under the car and everything is tightened up and the pipes are not hitting anything. The sound is very annoying.

Is this a normal sound to expect from running long tubes, without cats and a Borla exhaust?

JakeRobb

Get under the car with a rubber mallet and tap on the exhaust pipes hard enough to make them move like they do when the engine is running. Work your way back from the collectors all the way to the muffler, but focus on whatever area you think the sound is coming from. Listen for something similar to the sound you're hearing.

wrd1972

Okay I got under the car and banged on the pipes. All appears solid. I removed the heat shield around where the cat was, no change. Checked the u-bolts, they are tight.

The sound is mostly under load and has a rhythmic pattern to it, I really doubt its a rattle. I cant even be real sure that what I am hearing is actually coming out the tailpipe.

Does not do it simply revving the motor in neutral.

Can anyone explain this?

FlamingChicken

ive always noticed around 2500 a disgusting sound and just assumed it was exhaust inside the pipe hitting the bend. with my cats on it goes away, and again im assuming, bc they act as a resonator. not sure if thats what you are hearing as for me it mainly goes away after 3k

96' Formula WS6

I noticed a sound pretty similair to that in my 87. I believe it came from the crappy shop that built the first y-pipe and they actually stuck a 2.5 in pipe inside the 3 in collector and welded it inside there. I dont know if there is anything like that on your car but mine was also under load when the convertor was slipping at the lower rpm's.

wrd1972

I am now convinced that it is simply unwanted exhaust noise AKA rasp. When the cutout is closed it has the muffled machine gun sound and if you open the cutout it is the loud machine gun sound. Both sounds have the same pattern.

I am waiting for a local exhaust shop to get me a quote on doing mandral bent trual duals with a full size single dynomax X flow muffler or a pair of chambered powersticks out to the tips. If it ends up being an arm and a leg, I might get the Magnaflow catback since most claim it has no rasp unlike my Borla.

96' Formula WS6

True, I have heard that the borlas tend to be a bit on the raspy side

SS44Camaro

if its like a real bad rattle, it could be where your long tubes on the drivers side connect to the pipe, its right under the drivers side floorboard and it hits there when under load.

wrd1972

Nope not that. It has plenty of clearance. This is the normal rasp and drone from Borla, LT's and no cats.

I am considering either a bullet muffler or a powerstick (chambered) muffler in the I pipe. Anyone want to comment on either?

dr97z

I know exactly what you're talking about. If you give it some throttle and get the RPM's up, does it go away. It's just the sound you get after taking the cats out. Mine did the same thing when I took the cats out. Nothing to worry about, just give it some more throttle if you don't want to listen to it. Usually mine is worse if I'm lugging the motor a little.

wrd1972

Okay.
I bought a Hobart handler 140 MIG welder today. Been looking for an excuse to get one for years. TD's is as good as any other reason I can think of. Just contributed my bit to stimulating the economy.

I am going to try my best to learn to weld well before jumping in. I am going to try real hard to not do the TD's in a sngle weekend. I will be able to make them the exact way i want.

It appears that the conventional x-pipe like used in the Basssani will not work with my Midwest TA crossmember (mount). So the Bassani TD's are out of the picture except to copy. There is a narrow x-pipe at Jegs that will work for me:
http://www.jegs.com/p/JEGS/1130498/10002/-1

I am going to make a system that will allow me to easily and quickly install bullet cats at the collectors if I desire, install a pair of e-cutouts 18" back from the collectors to make it real FUGGIN loud and to tuck things up nicely for max ground clearance.