Originally Posted by TRZ06
I will chime in as I have had a tuned 335i and now on M3:
I had a 335i w/ KWV2 coilovers + RE-01R tires and now have an M3 w/ stock PS2
There are 3 main things to consider, here are my opinions on them...
1. Poise and stability: KWV2 by a small margin over the stock M3 with regards to rear-end poise and the ability to stabilize after being disturbed.
2. Handling limits: M3 hands down, I can hold more speed in a given corner/sweeper in the stock M3 over the 335i w/ coilovers and stickier tires. I attribute that to the LSD in the M3 and the different suspension geometry.
3. Understeer/Oversteer: 335i needs sway bars for neutral handling at the limits, and to where the M3 stock is VERY close to neutral.
You put the same coilovers and stickier tires on the M3 and you are now quite (and I mean QUITE) a bit ahead of the 335i in terms of overall handling.
As far as TQ, I am split on this one. On one hand I really miss the low-end TQ of the 335i especially w/ the TT I had in it, BUT it died out at about 6K. On the other hand, I do love the continuous TQ all the way up to redline in the M3.
Another factor is turbo lag, while minimal there is a lag in the 335i, no turbo car can replicate that instantaneous throttle response of a V8 N/A motor.
You could change out the suspension arms on the 335 5o the M3 arms for about $1,500 installed. Then you'd be talking a nice ride for much less than an M3, particularly for daily driving.