Well, actually I've had it for a bit longer but some girl named sandy stopped by and really messed up my week. I've recently had my performance exhaust installed and decided to give it a review. You can read that here... http://www.e90post.com/forums/showthread.php?t=754850
So I figured it would be really helpful to make another review, this time about my performance power kit, especially since there are so few cars with it and I could give a little insight on how both the power kit and exhaust work together with the car.
Ok, first the bad. I will admit that I was a bit disappointed. I did have my hopes up and was expecting to feel a much greater increase in power than I do currently. Now, I knew all along that I wasn't going to see the kind of numbers that a JB4 or cobb would produce. Truth be told, I've learned that I have become all about the OEM+ look of my car, and because I've wanted to keep that going with the performance of the car, I figured this would be the way to go. And yes you've guessed it, I care about my warranty lol. I don't want to start a debate, I know I could have gotten more power from other products. It just simply was not what I was going for. Trust me, there is a silver lining.......
Now, before people begin saying how much I overpaid, it's worth noting that I got both my exhaust and ppk secondhand from members on here. Brand new and installed, these would have have cost me close to $3000. In the end, I dished out less than half of that. Someone had bought the kit but decided to go another route.
What you need to know. There was a bit of confusion when I had bought this kit and with the help of Phil from Reeves BMW, we were able to clear it all up. http://www.e90post.com/forums/showthread.php?t=750328
Also because this is a software upgrade, my dealership needed to keep my car there most of the day. You should make sure you can get a loaner for the day.
So, as I said earlier, I had this kit installed the Saturday that Hurricane Sandy hit. And even after my neighborhood was cleaned up, finding gas to try it out was a problem. <Truthfully, after seeing all the damage, I couldn't in good conscious really go out and experiment. My heart goes out to everyone and I really do hope normalcy is restored!>
So yesterday, I was finally able to fill up and drove about an hour north to my girlfriends house, ~60 miles at speeds from around 65-80. It was on the highway where I noticed a big difference with the ppk installed. A difference that I didn't notice when driving around at normal speeds. It is extremely easy to pass someone at highway speeds! It's almost like when BMW developed this kit, they weren't really concerned with 0-60 times but more like 60-80 times. For any Top Gear fans, the first thing I thought of was when Richard Hammond tested out the Audi RS6 avant and showed how easy it was to pass other cars- granted, our cars are short 4 cylinders and a turbo. You get my point.
Also, anyone who already has a performance exhaust and is considering the ppk should know that the ppk will subdue the exhaust note. I love the sound of the performance exhaust but, I've grown to not be much of a fan of it at highway speeds (in 6th at around 3k rpms). It was the first thing my girlfriend had noticed, and she was not too happy listening to it all the way up to Saratoga Springs. The note is a little calmer, yet still retains both the exhaust burble and a nice aggressive growl at cruising speeds. From idle to around 2000 rpms the note is a growl. After 2000 rpms, the note gets a bit elevated, but not high pitched or mechanical like a Porsche flat six. The note is still there, just not as obnoxious.
When I got back to my neighborhood this afternoon, I decided to do a couple of aggressive launches, nothing crazy. It felt that around 3000 rpms the car gets a boost, almost like a constant wind at its back pushing it a little bit more than before the ppk was installed. It also felt that my shifts were smoother. The extra power, paired with the reduced back pressure from the exhaust make for a very nice drive and I think that's where BMW is going with these parts....
I made mention of being able to shift easier with the PE. Now I'm experiencing a much easier time passing people on the highway. I can't help but think that not only are these parts designed for performance gains, but also just make the cars easier to drive. On a 135 it's easy to feel these parts make it become more track oriented car, with its shorter wheelbase and better power to weight ratio. On a 335, they make the car feel like a higher performance grand tourer.
In the end, I'm pretty happy with the way the car has turned out. Sans the DCT gearbox, and dealing with xdrive, I've gotten a bit closer to seeing what living with a 335is is really like. I like the fact that I've made my car really stand out using OEM parts, and am happy with what I've gotten in return. I understand that many people can't simply justify spending the money on the PPK, but I still stand by performance exhaust and would recommend this combo to anyone looking to retain their warranty. I'm not sure if there is a breaking period to the ppk, but if there is and I feel or see any difference ill be sure to update this.