Underground Autosports at 18 Golf Center Suite A, Hoffman Estates, Illinois.

Like the others said - avoid this place. I had my BMW 335is in for Cobb upgrades and they cracked the audio cover. Took a while to figure it out, but these hacks didn't own up to the damage they did. Oil all over the firewall. Huge mess. On my X5, I brought it in for some routine maintenance (before I know the audio cover was cracked) and the car was given back to me in limp mode with the dash full of alarms, but they didn't do it. Right... Cost me $2k for BMW to fix their mess. Plus, I paid for a coolant flush and BMW said there is "no way that coolant was changed in the last year." Go anywhere else and avoid the nightmare.