I'm planing to pick up a set of Nitron R3's for my GT3 from my boys here in Taiwan German Motorsports.
they seem to have very good quality i've seen these in person. should be a great choice for M3's
Past: Gintani stage3 M3
present: Porsche 993RWB, 964RS America,996 cupcar, 964 turbo 3.6, 991C4S, i3 in September