08z51m6Ls3

Hi all,

Just installed TSP longtube Headers and catless x pipe yesterday on my base c6 LS3 M6 car.

Upon first start up, I noticed a leak immediately. The car had the NPP exhaust set to open and I could still hear the leak. Put the car back up in the air and inspected while engine was running. Noticed leaks at basically every connection from the primaries on back to the over the axle pipes (6 clamps total on this kit).

I adjusted and tightened down the clamps and it made the leak better, but i'm pretty sure it's still leaking a bit. Regardless, besides being much louder, I'm not really impressed with how the car sounds. Might be because the x pipe is leaking and some of the exhaust is making it's way out pre-mufflers, but I really don't like the way she sounds as compared to stock NPP open.

The car hasn't been tuned yet and the pop on decel is way over the top now with the headers.

Who else was unhappy with their exhaust note after longtubes/no cats? Did that change after getting leaks worked out and a tune done on the car? Will a tune even change the sound of the exhaust? Also, I feel like I'm down on power, haven't really laid into her yet but part throttle acceleration seems lazy as compared to stock.

I know I have got to get the bugs worked out and re-evaluate, but I'm hoping to get some peace of mind that the tone of the exhaust will change and sound better after I sort out the leaks.

Right now, the tone sounds fine at idle standing behind the vehicle but get on it and accelerate a bit and she sounds pretty raspy. When letting off the throttle to upshift into the next gear, the exhaust has a fluttering type sound.

Best way to put it is the exhaust note sounds rough, not smooth, linear, and loud like I was expecting while accelerating.

Also, no miss when scanning for codes, just the cat code since no tune yet.

As for fixing the leaks at the xpipe connections, it's a slip fit style so I'm thinking about just having a shop weld all the joints instead of the supplied band clamps. The clamps seem to be of high quality, and I'd rather have the clamps, but not if I have to keep chasing leaks.

Any downsides to welding? Not much reason to have to remove the exhaust outside of dropping the trans or diff, correct?

Thanks in advance for your feedback!

Kulprit7

Good timing, I just installed my TSP longtubes and catless x last weekend and got the car tuned yesterday. My car is an 08 z51 A6.

I did not experience any leaks. What i did was installed the entire system loosely, and then progressively tightened down all the clamps at the connection points. In the past I have experienced leaks at slip fit connections, and I coated the male end with high temp red RTV silicone before slipping them together and clamping.

As far as the exhaust note, when you go to longtubes and no cats through an open NPP (same as mine), it is definitely not going to sound smooth or linear. There is nothing in this setup that muffles any sound. You will hear absolutely everything that the engine is doing, including crackles and pops on decel. Luckily I happen to love it, but perhaps making your NPP valves active again will tone it down a little bit during normal driving for you.

My tune did not change the exhaust note at all, it still sounds like a beast! Feels noticeably stronger to me as well.

I want to thank Texas Speed for the headers, everything fit well and quality was incredible especially considering the price.

I also want to thank the crew at Complete Street Performance for the dyno/street tune yesterday.

Let me know if you have any more questions on the headers.

08z51m6Ls3

Thanks for that, Kulprit. I'm starting to think that my complaints are tied to the wide open NPP. I have the M2W switch and can run the system closed but my goodness over 3500 RPM when the baffles open the exhaust is RAUCOUS!!! WAY TOO LOUD for street driving ha, afraid I might get a ticket!

I wonder if there is any way I can keep the valves closed all the time, regardless of rpm? Wish there was an option to keep closed/open ALL the time rather than the 3500 rpm open that the NPP has from the factory?

Did you notice any loss of part throttle power/performance after installing the headers and before the tune? If so, did that change after the tune? I just feel like the car isn't as responsive down low cruising as it was prior. Might be that the loss of torque is just part of having longtubes installed and I need to ring her out to see the gains?

Thanks!

sevinn

Are the clamps the type that cover the whole joint or the type that just go over the larger side of the slip joint? I've had really good luck fixing leaks with the band clamp style that is initially flat but is meant to form to the shape of the joint.


To these points: NPP does sound pretty bad at part throttle to me in the wide open setting. A dashlogic can keep the valves closed all the time, but if you're going to go that far you may want to just swap to a different axle back that you actually like. Something like a borla or corsa touring setup sounds right up your alley.

Kulprit7

I would definitely try closing your NPP, although I am unsure of a way to keep them closed all the time. You could always trade for a non-NPP catback and probably make a few bucks on the deal.

It is definitely raucous, that's a good way to describe it. Like I said, I feel fortunate that I like it and can definitely see how somebody such as yourself would feel like its over the top.

I do not notice any performance loss, but I typically don't really "get on it" under 3000 rpm, and it pulls just as hard if not harder than before from that engine speed. Also, I didn't really do any pulls with the headers un-tuned. Although I'm sure the diablo tune I had was fine, I didn't want to risk any engine damage just in case. After the tune, like I said, car seems stronger everywhere to me, and that is what the dyno chart shows also.

Where are you located? If by chance you're near me, I can always meet up to help out a friend!

pyrodav

I did not like the sound I got from headers and NPP. I went with the B&B fusion and I like it much better. Sounds to me like you may want to try Borla.

schpenxel

Add a 1 way valve on the vacuum hose running to the solenoids and they'll stay closed all the time.

08z51m6Ls3

I'd love to see a tutorial on how this is done, wonder if one exists or if you have time, could you elaborate a bit?

Thanks

schpenxel

I'd have to see a factory setup to give much more direction. Mine has NPP but it was added later.

It's not that hard though--add 1 way valve after the solenoid that controls the flaps and air won't be able to go back into the thing that moves the flaps, thus keeping them closed. I did something similar on mine at one point but since it's not a factory setup the hoses and routing are all different.

Or buy dash logic and then you can just plug it in and control the flaps all you want. The power mirror switch acts as an NPP controller. If you set the switch to the left (as if you wanted to move the driver mirror) then it opens the flaps 100% of the time. Leave it in the middle position and it lets the computer control them like normal. Leave it towards the passenger side and they will stay closed 100% of the time

That's what I'd be looking at.

spoolngc8

Bringing this back from the dead as I just installed the TSP 1 7/8" longtubes, 3" offroad x-pipe, and a z06 axle back. The car sounds much deeper/louder but damn it got raspy sounding. I am suspect I have some leaks that need to be addressed but im not positive, I got called into work just as i finished bolting it all up so I didnt have the chance to get it in the air and check. I can just hear what sounds like disrupted airflow as I accelerate.. it sounds as if there is a leak while at partial throttle. Full throttle is too loud to tell. At idle it doesn't sound like theres a leak really.. I did the install with my father and he said it sounded good at the shop once we initially fired it up. Basically im just wondering - Does this setup warrant a slightly "raspy" exhaust note? Any video ive ever watched of a vette i've never heard such a raspy exhaust tone.. Could the z06 muffler flaps being open attribute to this sound? (I have the fuse pulled so they are always open while running) I am planning to bring the car to get the muffler mod done soon. Any input is appreciated!

08z51m6Ls3

Congrats on the new mods! I had to readjust, massage, and re-tighten my setup several times until it was right. As for the exhaust note, it's just loud and raspy without cats and the baffles open. Just the nature of the beast and I don't think you can change that without quiet exhaust or adding cats.

The difference in power is absolutely remarkable. My car put down 454 hp 450 ft lb after the tune.

Vararam
TSP Longtubes/offroad x
Open NPP
Tune

I couldn't believe my eyes when I saw the dyno chart! I would check for leaks and re-tighten all of the clamps. Good luck!