Installed GHL mufflers...now need some help

[ScottArizona]

Hello all. I just recently installed some GHL mufflers on my dad's 02 996 tip. THinking about getting some for my 99. The quality and fit were great, and the sound is just perfect with absolutely NO resonance or droning.

However, I can feel a slight exhaust leak where the muffler inlet pipe attaches to the cats. I've pretty much torqued it down as far is it will go (with the pipes hot even), and the leak is still present. I think what has happened is that the muffler pipe that attaches to the cat pipe via the stock double-clamp sleeve is just a bit smaller in diamter than the stock muffler pipe. Thus, I can't get the sleeve to seal up the entire circumfrence of the muffler pipe. In fact, the sleeve appears slightlycrimped in one spot, and this is where I can detect a small amount of exhaust leaking.

I took the car to the local midas, and they chuckled and said the leak was minor and not to worry about it. I'm anal about such things however, and the midas employee admitted to being very unfamiliar with porsches, so here are my three questions:

1. Will these leak cause any problems? Looks like the leak is after the o2 sensor, so it shouldn't cause any problems with the fuel mixture, should it?

2. Will these leak affect performance?

3. If the answer to any of these questions is "yes," how do you guys recommend I fix the problem? (the midas guy said they could weld it, but I'm hesitant to do anything that permanent).

Youre input is appreciated. Scott.

[1999Porsche911]

Hello all. I just recently installed some GHL mufflers on my dad's 02 996 tip. THinking about getting some for my 99. The quality and fit were great, and the sound is just perfect with absolutely NO resonance or droning.

However, I can feel a slight exhaust leak where the muffler inlet pipe attaches to the cats. I've pretty much torqued it down as far is it will go (with the pipes hot even), and the leak is still present. I think what has happened is that the muffler pipe that attaches to the cat pipe via the stock double-clamp sleeve is just a bit smaller in diamter than the stock muffler pipe. Thus, I can't get the sleeve to seal up the entire circumfrence of the muffler pipe. In fact, the sleeve appears slightlycrimped in one spot, and this is where I can detect a small amount of exhaust leaking.

I took the car to the local midas, and they chuckled and said the leak was minor and not to worry about it. I'm anal about such things however, and the midas employee admitted to being very unfamiliar with porsches, so here are my three questions:

1. Will these leak cause any problems? Looks like the leak is after the o2 sensor, so it shouldn't cause any problems with the fuel mixture, should it?

2. Will these leak affect performance?

3. If the answer to any of these questions is "yes," how do you guys recommend I fix the problem? (the midas guy said they could weld it, but I'm hesitant to do anything that permanent).

Youre input is appreciated. Scott.

It won't make any difference performance wise. If it bothers you. wrap alluminum foil around the section of the pipe that is smaller and then put the clamp on it. This will stop the leak.

[Izzy]

Scott,

I got GHL's too, and know exactly what you mean on both sound, and the pipe to the cat being a bit short. The Fabspeeds I tried fit perfectly, the pipe going to the cat must have been a 1/4" longer than the GHL's.

Nothing to worry about on performance or noise.

But here is what I did

1. Remove rear bumper and heat shields

2. Loosen the two nuts on the muffler and the clamp nut on the muffler side connecting to the cat sleeve

3. Get the wife or girlfriend (but not both at the same time, can be dangerous) to help next step

4. While you get on the ground and push on the mufler to get deeper into the cat sleeve, have the second person get the sleeve nut tight

5. Secure the muffler's nuts

6. Replace shields and bumper cover.

Worked for me on two cars, no leaks, no noises (for over a year). I really appreciate the GHL sound on the cabrio, on the coupe they are barely noticeable. But I recently had someone on a track day asked me what kind of mufflers I had, since they sound so "sweet". I can't hear a thing with the helmet on....

Enjoy

[Heidster]

I put some GHL's on ~3 weeks ago. Initially I was a bit "underwelmed" with the sound, at least from inside the car. My benchmark was my old SC that had SSI's and a B&B single outlet muffler. It was a very nice tone inside the car. Not too loud but I enjoyed going through the gears for sure. A neighbor thought it was one on the best exhaust sounds he's ever heard whenever I drove by. Anyway, as far as the GHL's, there is a bit of boominess in the higher gears, hard throttle up to ~2400 RPM. But its really not that annoying as the payoff comes from 3000 on up. I still hear about 50% mechanical vs. 50% exhaust note. (the SC being ~2/3 exhaust and 1/3 mechanical.) As many have said...the sound may change as the get broken in. The 996 has more sound absorbing material than the early cars. This may explain my initial impressions. I'm sure people with cabs would experience more dbs and a different impression. I'd rather be on the quiet side for now.

As for my install. ~5-6 hours total...rusty bolts/clamps = WD40, dremel tools, hammers and a hacksaw. I had to go to Home Depot for the longer hex bolts on the muffler brackets. (hope this does not effect re-sale $!!!) Anyway, I used new clamps for the tips as well as the sleeves that connect the outlet of the cats to the inlet of the mufflers. There could be a little gap between the pipes, maybe 1/4". I did not notice any diameter difference. I recall checking them with a caliper before assembly. I initially tightened the sleeves to the 34 lb/ft called for. One of them leaked slightly so I torqued them both to ~ 38 lb/ft...no leak.

The above post suggesting aluminum foil is worth a try. Did you use new clamps? You might try some sort of exhaust sealant but this might cause a problem down the road when trying to dissasemble.

Hope this helps. :lightbulb:

[ianwallwork]

Hello all. I just recently installed some GHL mufflers on my dad's 02 996 tip. THinking about getting some for my 99. The quality and fit were great, and the sound is just perfect with absolutely NO resonance or droning.

However, I can feel a slight exhaust leak where the muffler inlet pipe attaches to the cats. I've pretty much torqued it down as far is it will go (with the pipes hot even), and the leak is still present. I think what has happened is that the muffler pipe that attaches to the cat pipe via the stock double-clamp sleeve is just a bit smaller in diamter than the stock muffler pipe. Thus, I can't get the sleeve to seal up the entire circumfrence of the muffler pipe. In fact, the sleeve appears slightlycrimped in one spot, and this is where I can detect a small amount of exhaust leaking.

I took the car to the local midas, and they chuckled and said the leak was minor and not to worry about it. I'm anal about such things however, and the midas employee admitted to being very unfamiliar with porsches, so here are my three questions:

1. Will these leak cause any problems? Looks like the leak is after the o2 sensor, so it shouldn't cause any problems with the fuel mixture, should it?

2. Will these leak affect performance?

3. If the answer to any of these questions is "yes," how do you guys recommend I fix the problem? (the midas guy said they could weld it, but I'm hesitant to do anything that permanent).

Youre input is appreciated. Scott.

In answer to your questions, no the leak will not cause any problem or performance penalty. To stop the leak, simply get two new clamps. The old ones are probably distorted - mine were when I took them off when fitting my PSEs. Also the spec has changed - the new ones now have bigger / stronger bolts and seal better. Also torque up the clamps before fully tightening the 3 nuts that hold the silencers to the car.

On a different note, don't forget to reset your DME now you have the new exhaust cans. This will cause the unit to recalibrate and you will quickly see any performance gain the exhaust might bring. To reset the DME, turn your ignition to 'on' (all dash lights on but motor not running). If you don't do this the alarm will go off. Then disconnect the negative battery terminal. Turn the ignition off and leave the battery disconnected for an hour or so. Re-connect and go for a drive and I think you'll be very pleasantly surprised!

Ian

PS. After you've re-connected you'll need your radio code as it will ask for the pass code. You'll also need to run your windows up and down a couple of times before the one-touch will work.

[ScottArizona]

Thanks for all the responses guys. I think I'm going to try the tin foil trick. One question: To reset the computer, isn't it sufficient to just disconnect the neg. battery cable for 2-3 hours? (i.e., necessary to leave the key in the ignition?). Thanks, Scott.

[Loren]

To reset the computer, isn't it sufficient to just disconnect the neg. battery cable for 2-3 hours?

It is more like 5 minutes.

[eben]

I put GHLs on a few months ago and haven't done any DME reset.

I have not heard about this before. Anyone know how/what the computer is able to sense different with the new mufflers that would make a difference to its setup?

[Izzy]

Eric, I never have either. I thought the DME is changing based on closed feedback loop, and will adjust anyway to the new conditions.