We wanted to share this wonderful review by an Agency Power customer on the forums, for anyone considering an Agency Power E92 M3 Exhaust:

“It’s been a while since I acquired and installed my Agency Power exhaust. Recently I purchased a Fabspeed resonated Xpipe and Fabspeed high flow cats from a user on this board. It was installed immediately afterwards. I figure it would be helpful to post up a review, as well as a few videos to prospective buyers of this exhaust combination.

Agency Power Exhaust w/connecting pipes
My E92 M3 was stock as stock could be at this point. I was out of my comfort zone, as this was my first non-Honda. I wasn’t familiar with the myriad of exhaust system choices. After viewing video after video online, I still could not make up my mind. My requirements with an exhaust system were as follows:
Not obnoxiously loud
Did not drone
Was bolt on
Reasonable price

I visited Bart at AUTOcouture at this shop in Hillsdale, NJ and heard his Agency Power exhaust in person. It was absolutely perfect. I was surprised that he had no additional modifications and his car simply sounded exactly the way I wanted. He was even nice enough to take me for a ride to prove that there was no drone.

I admit I was a little slow to actually purchase since I’m always guilty with buying things like this, but I finally did. When it finally came in (after some issues with UPS), I immediately unboxed it, took a few pics, and started the install process. I’m very pleased with the price as well.

Performance wise, I didn’t really feel anything at all, and I didn’t expect to. There was absolutely no drone (although that is subjective as some say the OEM system has drone). In that case, I would say it was equal to the amount of drone the OEM system has. Upon cold startup, the system was significantly louder than OEM at idle. It literally rumbled in your chest if you were standing close by. About 30 seconds later, the idle returned to OEM levels.

My only complaint is that the titanium tips seemed too short. If you bent down to look at the system, you could see the ends of the tips very easily. I suppose I could probably adjust the system to make it flusher to the bumper, but I’m lazy. My left side tips protrude ever so slightly more than the right side. It’s not noticeable except to me. Other people with this exhaust stated the same thing, so I’m not alone.

After a while, I started yearning for more power. I got a Macht Schnell air filter and the Powerchip stage 1 ECU reflash. Honestly didn’t feel it that much, but it was better. Reading and posting about Xpipes showed me that the Xpipe modification would free up quite a bit of power (probably the most out of any N/A mod).

Fabspeed resonated Xpipe & Fabspeed high flow cats (w/O2 extenders)
I was very concerned since everybody said that an Xpipe significantly changes your exhaust volume. Even people with the OEM exhaust and aftermarket Xpipe had a very loud car. My Agency Power alone was almost on the verge of being too loud, so I was VERY hesitant on purchasing an Xpipe. Unfortunately, I was not able to hear an M3 with one.

My other concern was I absolutely did NOT want to cut my OEM system and I absolutely did NOT want to fail emissions inspection. I was reduced to a few limited choices (resonated pipes with high flow cats). Unfortunately, these are usually significantly more expensive due to the cats.

I was lucky enough to speak to a member here willing to sell his setup for a great price. We both drove over an hour each way to meet up. Unfortunately, I do not have pictures of the install, only video.

Performance
I never “feel” any performance modification other than a supercharger or turbocharger. However, I was pleasantly surprised that I could definitely feel the addition of the Xpipe. The car definitely reved up faster and the top end was simply ridiculous. I’m sure it was due to the combination of my other modifications (specifically the Powerchip flash). After 6500rpm, the car was an absolute beast. I now need to somehow get the Powerchip stage II flash since it takes advantage of xpipes with high flow cats.

Sound
On cold start, the sound again was very loud, but pretty much exactly the same as having the Agency Power exhaust rear section alone. Perhaps it was a tiny bit deeper. On idle it was a little throatier, but hardly noticeable. On idle revving to ~3500rpm, it sounded almost exactly the same as having the AP rear section only.

The major difference in sound is when you’re driving around in town in the lower rpm range. It’s significantly louder, almost too loud for me. After a couple of weeks however, I am used to the sound and it does not bother me. I do get somewhat self conscious if I’m driving through a small development with people around. Don’t get me wrong, it is definitely not obnoxious at all.

On the highway at cruising speed (60-80mph), the car sounds pretty much just like stock. However, as soon as you step on the gas, the Xpipe noise definitely takes charge. It’s much throatier and has a mixture of “exotic” and “muscle car” tones. This is what I hear from the inside, and a few people driving behind me during rallies have said the same thing. I have yet to get a video of me driving from outside. If you’re literally on the gas on the highway, there is some drone, but it’s not unbearable at all.

All in all, if it was a tiny bit quieter around town, I would be 100% happy. Obviously with the hundreds of exhaust system combinations, nobody is going to be 100% happy, but I think I have it pretty close.

Misc
I’m running the supplied O2 extenders after the high flow cats, and I have not encountered any CELs. I’ve been driving on this for several weeks now from a track event, to a charity rally, to putzing around town and no issues have popped up. I’ve also driven in temperatures from 75 degrees to 32 degrees so far.”