Originally Posted by eric@helix
Not good ones. If drivability is a top priority, the GIAC is the smoothest and most factory like in my experience.
+1 Smoother than factory actually for 4 yrs now
2007 E90 335i, TiAg, 6AT, ZPP, ZSP, ZCW, 6FL, HD
Quaife lsd, ETS fmic, GIAC s/w, Dinan intake/exhaust/oc, Koni/M3 susp, Apex Arc 8, Mich PSS