I got my SLP LT's installed last week.

They sound bad ***, but one thing is annoying the hell out of me. During idle and at low speeds (35mph and lower it seems) the Y-pipe is banging against the bottom of the car. It sounds like it's right underneath the passenger seat. Anyway, I take a look under there, and right where the catback and the Y-pipe meet, it looks like the pipe is sitting really close to the frame. This is where I suspect the banging coming from.

I asked the shop that installed the LT's for me... and they told me there really isn't much you can do with moving the Y-pipe further from the body of the car, because where they sit is at the mercy of the LT's.

My question is... if you experienced this noise, how did you fix it?

I was thinking if all else fails, go to the muffler shop here in town and have them cut that piece of pipe out, and re-fab a different shaped one, one that works around the suspected trouble spot.

 

Most people just put a piece of heater hose inbetween the car and the y pipe. But for the record I've had mine for 4 years and have never had them bang on the floor, on speed bumps and rocks and anything else on the road, but never on the floor of the car.

 

The fix for some has been to use poly. motor mounts. My friend installed some last summer and it seemed to fix his problem for the most part.

 

Heater hose whould melt and make nasty smells wouldn't it?

 

I haven't heard of it melting yet, but then again you won't know till you try.

 

I guess I'm going to have to jerry rig it somehow...

... the shop that installed them took a look at it for me, and they said there isn't much that can be done to it.

Basically, there is only like 1/8" clearance from the pipe to the floor pan (I know I said frame earlier... sorry). The banging is right where the Y-pipe and the cat-back are welded together, directly above the crossbrace. So it looks like a real bitch to get to.

You can't really hear it on the outside, but man can you hear it on the inside. It just bangs away at low idle and from shifting from N to 1st, directly under the passenger seat it seems.

Ah well... I'll get it to quiet down somehow.

 

Thunder Racing sells a "LS1 Y-pipe bump stop hanger" you might want to look at. Search for product number 95-LS1-HR.

 

I took a look at that product... but I don't think it's going to help... considering where the banging is coming from. That hangar looks like it's designed more for the front of the Y-pipe.

I don't think it would fit where the banging is coming from (above the crossbrace where the catback and Y-pipe meet)

 

It seems like some have this problem and othere's don't, ask the installer if they tightened the header bolts before installing the y-pipe. Adjusting the y-ipe after the header bolts have been tightened is almost impossible. Also take a look at the clamps, if the threaded part is facing up that could be your problem.

 

From my experience it's only the SLP's that have this fittment issue. The hookers and flowtechs fit wonderfully, and are easier to install. The SLP headers also sit very low under the car. I don't know what they could have done to have the y-pipe too close to the floor as all the SLP headers I have seen sit too far from the floor and that's why they have issues with speed bumps and what not...

They must have done something differently, that makes them sit too high..

Chris

 

If the Y pipe can be taken off any decent muffler shop with a bender should be able to flatten it out just a little and you will have no problem.

 

Yep... that was it.

They tightened the header bolts down before putting the Y-pipe on. I took my car back to the shop and asked them to loosen the header bolts and re-adjust the Y-pipe.

It didn't move the Y-pipe that much, but it was enough to keep the pipe from banging up against the floor.... and well, that's what counts.

It's amazing how much 1/4" make a difference!

 

does this have to be welded to the bottom of the car, or is it a bolt-in replacement?

 

Not sure, kinda looks like you can drill a hole where you need to mount it. TR or Mufflex should be able to answer. BTW, a friend of mine solved his banging by having a muffler shop cut an old valve spring and tac weld it between his Y pipe and floorboard.

 

ive also heard that if you have your exhaust weleded, instead of the u bolts, you can get rid of some of the flex that causes the banging. anyone else heard this?