Microtech82

So....

Took six hours with two buddies (one of whom left about halfway through the job...). Hardest part was getting the actual headers up in the car since we only had Rhino Ramps

Switched out all the goodies like plugs and wires. Didn't do the mounts because I already spent $250 on battery, extensions, wires, plugs, etc. and didn't have the time *shrug*

Car feels and sounds AMAZING. Stock with cutout was really bassy and droned inside a lot, especially around 2k rpms. New exhaust got rid of the bass drone while increasing volume. GOOD volume. The tone is great, no rasp, sounds like a bad-*** pro drag car. I'm not sure how to describe the sound. I guess like a rapid clackety noise. I think I heard somewhere that that's the sound of the valves slapping shut?

The car sounds great and runs great. VERY pleased with my purchase. Thank you, everyone for helping me with all my questions!

Tall Guy

iTrader: (1)

One thing to remember Microtech is that here in ABQ we are down on power about 20% or so due to the high altitude. A lot of the mods we do are just getting our cars back to 'sea level power' so to speak.
My 99 HOSS with the LPE top end kit was a monster at sea level when I was in Dallas and other cities near sea level but lost a fair amount of power up here in ABQ. It had at nearly the same power at sea level being stock as it does up here being modified.

Microtech82

Oh I know. That's why I was saying we're lucky to hit low 14s with stock LS1s here. Probably the main reason I'm not going to waste money on dyno numbers...I'd rather be happy with how the car FEELS than be disappointed by coming up short on numbers. I guess the only good thing about the elevation is that it affects EVERYONE so our cars are still faster than most of what's out there on Montgomery

DeLaRosa25

iTrader: (10)

Wait until you get a stall..Then the fun really begins

Microtech82

Ok....issue after the install.

Took the car to work today. Sounds killer from cold start - real loud and "clackety." After engine warms up, kind of quiets down a little in low rpm range while idling or crusing. Revs like a beast. Ever since I bought the car I had backfire issues when letting off the throttle from mid to high revs. Didn't know if it was related to exhaust leaks or bad plugs/wires but it is now gone and this is the first time in over a year that I have been able to rev the motor with no boom-booms.

So...
idle: no problem
revving while sitting or moving: no problem
accelerating below 2,000 and above ~2,700 rpms: no problem
HOWEVER there is a horribly loud whacking/banging noise for just a moment when the engine roars between that 2k and 2.7k rpm mark WHILE UNDER LOAD. Scared the crap out of me the first time I heard it because I thought my car took a and was about to lose the exhaust on the road. I don't have tools here at work but was able to do a quick peek under the car and don't see any issues with the install...everything appears to be bolted tight and tucked up right where I left it.

I'd like to know what you guys think. My hopeful guess is that the exhaust is causing some resonation effect around that rpm range (this was also the range that I had LOUD drone with the stock exhaust + cutout) and is vibrating/banging against metal parts during this short period of the acceleration. When we were attempting to pull the stock Y off the I pipe we noticed that the whole damn rear exhaust was sliding back and forth by a couple of inches so I'm wondering if the exhaust is loose at some location between the cutout and tips...

Any suggestions? I'm definitely going to crawl under the car this afternoon but I'm wondering if it will be safe to drive home from work...

Roarin_8

iTrader: (5)

If you didn't have the noise before the install then the exhaust is banging the floorboard somewhere. Since it's doing it under load, open the hood and move the throttle cable to those rpms so that you can hear where the noise is coming from.

Microtech82

So this jackhammer noise at those specific rpms is attributed to the pipes hitting the floorboard? How would I go about fixing that? I don't have the time/money for replacing the motor mounts...especially after just doing the install I am completely against getting back under there to switch mounts...

Could I maybe massage the floor board up to provide more room, or possibly get a ****-ton of header wrap and wrap the pipe at the offending location until it's snug up against the spot it's hitting? I'm looking for an easy fix, nothing fancy.

Roarin_8

iTrader: (5)

Check it first to see where it's coming from, then you can plan what to do afterwards.

Microtech82

Update:

No need for a fix. What I am hearing is a trumpet sound that was just so damn loud I couldn't comprehend what I was hearing haha I've actually found some "trumpet" vids here in the forum so I know it's normal. I must say that I actually like it now that I know the car isn't falling apart on me haha

So much traffic that I FINALLY was able to rip through the gears once before getting home. VERY pleased with the lt/ory/cutout combo!

Roarin_8

iTrader: (5)

So rasp was the issue....good to hear that it wasn't anything else.

Microtech82

I have no idea. Honestly I am completely lost when it comes to rasp. I'm never sure what rasp sounds like. I was under the impression that rasp sounded like kinda like a fart cannon.

This:
https://ls1tech.com/forums/generatio...-included.html
is exactly what is happening. You're saying this is rasp?

Roarin_8

iTrader: (5)

Yup that's rasp, SLP Loudmouth with no cats and with longtubes is going to sound like that and it gets worse with a cam. Reason why I changed the loudmouth bullet out for the Borla XR1 when I had my cam put in. You can also hear the trumpet but not as bad as it could have been.

Microtech82

Wow...so I guess I was completely off on what I originally thought of rasp. So as long as this is normal then I guess I don't mind it. The only thing that kind of blows is that, even though it only happens in the mid 2k range, I have those long 2.73 gears so it kind of lasts for a while when only accelerating with like 1/2 throttle. Now that I've been driving the car around for a couple of days it has lost a bit of the ohmygodwhatthef***isthatnoise effect on me, but now that I'm getting use to it I'm picking out a tin rattle/buzz along with the rasp. Could this be a vibrating heat shield, or is that also part of the rasp? I don't hear it under easy driving or WOT, but that rattle is definitely coming through when that rasp/trumpet is at full volume when I give it a healthy dose of throttle while low in a gear.

Roarin_8

iTrader: (5)

I know what you mean about the 2.73s, I still have those. Don't know, I don't hear any tin rattle/buzz in my exhaust, try looking under the car and see if you are getting any rubbing.

Microtech82

I'll definitely climb under the car this weekend to check it out. I'm still fairly confident that what's left of the stock exhaust is loose somewhere. I was pretty surprised when the whole damn stock catback was moving back and forth when I was trying to get the stock Y off of it. This was my first time working on the exhaust so I don't know if it is SUPPOSE to move like that but I thought it was really odd that it did so *shrug*

Microtech82

I've read a bunch of posts about the tinny rattle being due to the heat shields... I had a chance to bang on the exhaust and can't detect any rattling, so I'm HOPING it's the heat shield vibrating when I hit that raspy sweet spot and the dBs skyrocket. This is getting extremely annoying driving around and having my car sound like it has a damn fart cannon on it. Some people say it's ok to remove the shielding but....I dunno.... Seems like GM put the shielding there for a reason...

Anyone want to chime in with their .02?

Tall Guy

iTrader: (1)

What part of town are you in? Maybe you can swing by my place and we can check it out, i'm up in the NE heights area...

Microtech82

I live right by Cottonwood Mall :/ I might take you up on that offer if I can't they this figured out in a couple days but I am making progress; I found a spot where the Y is hitting under the driver's seat and I'm gonna make a bump stop for it. I might have thought of a way to stop the heat shield from rattling as well.