Got the longtubes installed today

Sonic04GT · Oct 19, 2010

I like the throatier sound of the H-pipe as opposed to the X but I feel like I lost bottom end torque and the car actually sounds quieter under 3k rpms. Has a nice growl when I open it up though.

Is this normal?

Completely different sound going from the O/R X and stock manifolds to the LTs and O/R H. Thinking about maybe switching to Magnapacks since I think this catback is getting pretty rusty and beaten.

Sonic04GT · Oct 19, 2010

if it matters, it has the default 87 Diablo tune I installed a while back

BurningRubber · Oct 19, 2010

LT's quiet things down until you mat the gas, nothing to worry about there.

As far as losing bottom end, not sure. I was always under the impression longtubes help with low end grunt as well as top end power.

Sonic04GT · Oct 19, 2010

Thanks for the reply. I'll have to get down to the track and see what's going on I'd like to get it dyno'd too for ****s and giggles.

Dark04GT · Oct 19, 2010

My LT's definitely quieted things down, more so down low than at WOT. I'm actually looking at a louder catback right now to compensate.

I didn't notice any decrease in performance down low but I did notice a little more pull up top.

Sonic04GT · Oct 19, 2010

Maybe it's just me. I just did a 2nd gear pull and it didn't feel as powerful. I do my 4k RPM roll and punch it in 1st tomorrow

Only cost $375 for the install, surprising. Was initially $300 but it took an extra hour due to fitment issues.

Tim2002GT · Oct 19, 2010

Thats a pretty good price for LT installation on these cars. Mine quited down a bunch when I put LT's on it, until I went WOT. Mine definately pulls harder above 3k rpm, under it is about the same as before.

Deleted member 38176 · Oct 20, 2010

I noticed a big loss in low-end with just an O/R H but much more pull up top. I think that on these motors, freer-flowing exhaust affects back pressure pretty significantly and thus affects low-end TQ production. However, as RPM's increase the importance of BP is deminished and the increased flow of exhaust gases allows for much improved performance up top......I think lol.

Winters98GT · Oct 20, 2010

You're not loosing anything down low, probably feels that way because the car is not as loud. LT's will provide more TQ than stock manifolds.

bhuff30 · Oct 20, 2010

Yup, absolutely. An offroad H or long tubes are not going to hurt low end torque. Back pressure is a badly mis-used term and I want to clarify that a little. You want to as little back pressure as possible without hurting exhaust velocities in your operating range. So the real concern is exhaust velocity. Going to 3" pipes would significantly reduce the exhaust velocity and hurt low end torque. Similar is true on the header primaries. A 1 5/8" primary on your header will be fine. If you go bigger than 1 3/4" primaries, then you would probably loose low end torque and gain some top end. Even bigger, and you would probably loose power over the entire operating range.

Winters98GT said:
You're not loosing anything down low, probably feels that way because the car is not as loud. LT's will provide more TQ than stock manifolds.

joshjwc9 · Oct 20, 2010

If you really want to feel the difference try switching to a 93 tune! (I think you said somewhere you still had a canned 87 Diablo tune.)

Sonic04GT · Oct 20, 2010

Thanks for all the replies. That's a good point on the car being quieter and possibility causing me to think it's not moving as fast haha

I was looking at the stage 8 box of bolts today and noticed there was a bunch of the pointy things left over, which I believe they give a bunch of each size so you can choose....BUT there were also 2 header bolts left...

Not sure if this was manufacturer defect or this guy didn't put 2 bolts on somewhere...Gonna see if I can reach my hand down there today and feel for 8 on each side.

Could this cause any issues? I'll probably take the car back to him if I can't get it on myself.

I was recommended to him by 2-3 people so he's supposed to be pretty good, and that price really did surprise me, especially with the original quote of $300 before he needed another hour.

I know the SCE gaskets I gave him are embossed "this side out." Hopefully he noticed that too I HATE exhaust leaks.

I definitely still hear something but could it be the valves/lifters? Is this common?

As far as back pressure and exhaust velocity...the Magnaflow catbacks turn into 3.5" tips I believe, how do you feel about that? Thinking about maybe replacing it anyway. I hear funny rasp noises here and there and it doesn't look that great.

BurningRubber · Oct 20, 2010

No the valve and lifters should not tick unless they are worn badly or are failing/have failed.

Did you notice the tick before the header install?

And the tips aren't going to do anything as far as changing the size for performance/adjusting exhaust flow unless you went to a much smaller size and constricted the flow of exhaust.

Sonic04GT · Oct 20, 2010

BurningRubber said:
No the valve and lifters should not tick unless they are worn badly or are failing/have failed.

Did you notice the tick before the header install?

And the tips aren't going to do anything as far as changing the size for performance/adjusting exhaust flow unless you went to a much smaller size and constricted the flow of exhaust.

Yeah it kinda seems like it's been there for a while, but could have been an exhaust leak with my stock manifolds. These LTs shouldn't be leaking. I'll have to get a video tomorrow, maybe you guys can tell.

BurningRubber · Oct 20, 2010

What kind of noise is it, where about is it coming from the engine?

Spark plugs can tick if they back out. It's usually a sign they're about to blow out of the head, may not be a bad idea to check them.

Sonic04GT · Oct 20, 2010

BurningRubber said:
What kind of noise is it, where about is it coming from the engine?

Spark plugs can tick if they back out. It's usually a sign they're about to blow out of the head, may not be a bad idea to check them.

I'm deaf but it kind of sounds like it is coming from the driver side valve cover. I need to do a thorough inspection of both sides and get back to you. It's hard to pin point, but I will also post a video.

It's not really noticable unless you rev it. The only time it really stands out is if I'm next to another vehicle or driving by a wall you can kind of hear the tick/whiz.

Sonic04GT · Oct 21, 2010

Not sure if you guys can tell, but here's the video. You can kind of hear it on the rev.

YouTube - MVI 0630

blackfang · Oct 24, 2010

An exhaust leak can make a ticking type sound.

Granted this was with a 4v, but I notice a nice increase in low end power and the car was quieter until I mashed the gas.

BlackArtemis · Oct 27, 2010

I just finished up my Lt's this weekend as well.
BBK Lt's with a catted H and SLP LM1. She quieted down a bit below 2500rpms, but at 3k+ she screams. Actually a bit too raspy for me, but I'll live with it.

As for power, it feels like she gained it all in the top end, feels the same down low as stock, but once she hits 4k+ she pulls a bit stronger.

Got the longtubes installed today

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