I have tested with a stock 335 when my buddy just bought it, UK spec M sport. Its pretty much neck to neck from stationery and rolling start as well, just keep the revs up and should not be problem. But once he installed Proceed, then just bau asap....with downpipe and new software, not even close. Around corners, from Karak toll to Gombak was altogether a different story. I could light up a ciggie and finished it before he arrived
Same thing in Sepang also, even with KWs and H&R the 335 just doesnt handle as well as an E46 M3, let alone the E92 M3. The steering ratio and the whole suspension setup is different.
The 335 comes in 2 variants, the earlier one uses a twin turbo engine codenamed N54 WITHOUT valvetronic. This unit has higher modding potential, those that want to go about 500bhp, can change the turbines. Look for the local proceed dealer, he is the man! The later one with DCT uses N55 engine WITH Valvetronic and single Turbine (twin scroll). Horse power remains the same, but the torque delivery comes in earlier by 300 rpm due to the twin scroll piping plus valvetronic, and a little more efficient.
The 326hp version as Beemer has mentioned is a tuned up version of the N55 engine, used in the Z4 35iS initially. The lastest 640i Grand Coupe and M135 use similar engine.
Cheers