Chimes, blinker sound, Onstar sound and steering wheel controls are the benefits of getting special harness(es). If you don't care about any of that, then you should be fine with just splicing it into the existing radio harness.
Edit: Just remember that your "lights on" warning chime won't work either. I drained my battery twice since I disconnected all annoying chimes lol
Black 2010 SS/TC – G85 | ZFR6758 | Term2 tuned | 479whp, 470wtq | Built internals | Cryo'd 4.45 | CM S4 clutch | Hahn CP | ZZP IC | Forge BPV | Hahn 3” DP and Catback | Hahn CAI | Ported head & intake | LE5 TB | Opel injectors + custom 5th injector | ZZP S3 cams | 82# valve springs | 420lph E85 LPFP | Custom FM oil cooler | PRS YYZ v3 & Koni yellows | PRS XXX bar | PRS rotated mounts, rear bushings & TCABS | PRS PCV | PRS Racing oil pan | PRS brake ducts
Last edited by colodude18; 12-03-2013 at 09:46 PM.