Like any E46 M3 you'll notice the brakes are a bit weaker (even weaker than my Z4 M) and the exhaust has a distinct rasp in the upper rpm region. The vert is 350 lbs. heavier than the coupe so that absorbs some thrust. But top up or down it's a blast. Tight, small, beautiful to look at, and top down the sound of the motor at full tilt is intoxicating. You should check into the ESS DME software to enhance the power. You can even raise the rev limiter and erase the speed limiter with the software. I've only had mine since Oct but plan to install KW V2s this year to improve ride quality and street cornering and at some point I'll improve the brakes. Check to make sure you don't have any subframe issues and depending on the miles you may want to consider new RTABs.
If you want to get some power back, you can always go to the Euro header and/or swap out the final drive ratio to the 3.91 or 4.10. The 3.91 is what the car should have come with. 3.62 is too tall which is why acceleration is what it is. With a 4.10 it's every bit as quick as your E92 M3.
Enjoy the better fuel economy!
'08 Carrera S 6MT Guards Red/Black ext leather, Carbon fiber pkg, sport exh, sport chrono +, PASM, Nav, Bose, 19" forged turbos, red tranny tunnel
'07 MV Agusta F4 1000 R 1+1, Corse Red/Silver, RG3 race pipes and factory race ECU