Resale value? Its a lost cause. Any car is equity dead off the showroom floor-add your payments/mods/insurance/upkeep and you'll realize that its pointless.
Enjoy the mighty V8 before the onslaught of the turbo burble. Nothing from M in the near future will ever sound this good again.
2011 Alpine White/Fox Red E90 M3. Sunroof Delete/DCT/No power seats/Square Apex ARC8s+ PSS /ACM Exhaust Mod+ EAS Tips