I’m into M3’s (E36, E46) and I have never liked the Dinan modified cars or felt the need to get one because M3’s come from the factory highly tuned. The e36 European version has a motor where some parts of the design was taken directly from F1 cars. Euro M3 Engine, "the best in the world after McLaren F1" | BMW M5 Forum and M6 Forums
Also, the Dinan package is also very expensive and I would rather modify my own BMW (if I had one) at a race proven BMW shop then go the Dinan route. Are Dinan parts overpriced?
All around though, BMWs are expensive which is why I’m a Ford guy. I hope to get my hands on a 1993 Cobra soon that’s about a 13 second car from factory for 8 grand used. Throw another grand or two into the motor and I’m low 12’s. To run 12’s in a BMW you’re shelling out thousands of dollars and you’re going to need a blower or turbo kit.