There is quite a difference between the E90 M3 front roll bar and the E90 bar. The E90 bar tapers down in the middle and at the ends of the bar where it curves making it less rigid than the M3 bar. I've driven similar cars with the M3 front bar and OE sport bar and the M3 bar definately has less roll, but it affects ride quality a bit on bumpy roads.
I have the PS front sway bar, which is perfect for my car, and the 14mm rear bar. With 265 PSS's, PS springs and an LSD, I wish I had installed the 15mm rear bar from the E93 335i. Those PSS's stick like glue and make the rear feel a little soft when pushing it.
Most folks will probably tell you to get E90 M3 front and rear bars. I think that rear M3 bar is too stiff for a non-m. The M3 weighs a bit more, has a wider track and a much better LSD. imo, get the E90 M3 front bar and the 15mm E93 335i rear bar OR the Dinan rear roll bar.
2007 E90 335i, TiAg, 6AT, ZPP, ZSP, ZCW, 6FL, HD
Quaife lsd, ETS fmic, GIAC s/w, Dinan intake/exhaust/oc, KW/GC/M3/Meyle susp, Apex Arc 8, Mich PSS