Hi All,

I recently purchased an used Agency Power exhaust system for my 01 996TT. I picked AP because it was advertised as no drone. The previous owner sold his car and said he had about 20K miles on the exhaust. Originally, I picked up a second stock exhaust system with the intent to do the TJW mod and bore out the cats, but this AP exhaust with cats came along and I thought would be better choice.

So install went well thanks to all the posters on this forum. However, man...does it drone. Between 2K-3K rpm under load...it resonates in the cabin. Above 3K rpm, it is nice and quiet. So living in LA and constantly in traffic, the drone is horrible. I am actually considering removing it and going with my original plan.

Also, last weekend, my car threw three codes: P0420, P0430, and P0156. I assume it is related to either a failing O2 sensor or the cats in the exhaust are failing.

So, is the life expectancy of these aftermarket exhaust systems about 20K miles or did I install this exhaust wrong or is "no drone" really subjective and this is actually pretty good sound wise?

I tried searching and found no customers of an AP exhaust system complaining of drone. Could my exhaust gasket at the turbo be leaking? I reused the exhaust gaskets.

My car is pretty much stock with the exception of an EPL tune.

Thanks.

 

I can't remember specifically during my research for an aftermarket exhaust but i remembered to steer clear of the AP exhaust for the reason of drone so there is nothing wrong with your exhaust that is just the way it sounds. I settled on a europipe stage 1 exhaust. All the performance gains with 0 drone and it sounds awesome too. I guess the only downside with compared to many other aftermarket exhausts is you don't really get much weight savings compared to stock. Life expectancy will depend on many different factors but im sure the average guy will get far more than 20k. I fully expect my EP to last as long as I own my car which should be many more years and 10s of thousands of miles. Your cats are the main thing that will eventually wear out and the better quality the cats the longer they will last.

 

Iv'e had an AP exhaust on my car for about 1.5 years have zero drone and still happy with it's sound. Maybe your cats are going bad?

 

How many miles have you put on during the 1.5 years? It's not loud when you go from light to light with the RPM range between 2-3K rpm? I don't even think the exhaust is loud at idle. I just get this loudness within that rpm band. I'm pretty sure as exhaust get older, the sound deadening qualities start to fade...just trying to figure out if 20K miles is a lot.

 

Around 6000 miles. I wouldn't say it's loud between 2-3k rpm's but sounds more aggressive then my stock exhaust for sure.

 

Then I am guessing that the deadening material is probably worn down at 20k miles on mine. I have 65K miles on my car, so I think the O2 sensors are prolly getting tired as well. Thanks for the feedback everyone. I think I saw a thread somewhere that people's exhausts were getting louder over time...so it makes sense.