I recently purchased an E36 M3 after 6 months of not being on track with my 335. The 335, as we all know, is finicky and as you progress with your driving it, often, can't hold up. I had ER OCs, no tune, but it was an AT. I didn't see any way to make it track worthy, hence, the M3.
This is a little comparison. I just drove my stock (just had ARC-8s with NT01s) E36 M3 with 209,000 on it at Infineon. Lots of clean laps so the times are a great indicator of it's track worthiness and cost.
Comparing to a 335 with TC Kline DA sus., Code 3 Intercooler, ER race OCs, R888s, StopTech BBK, full chassis setup with M3 bits and bushings. I probably spent 70,000 on mods and the service.
I paid 5,200 for the E36 and put another 5,400 in to make sure it was track worthy: ARC-8s, NT01s, fluids, worn bits, and a brake rebuild including race pads and SS lines. That's it.
You are so much more connected to the driving with the M3. It's raw and I love the MT. Everything feels so uninsulated when compared. The soft suspension with stock is a challenge but that's part of driving.
My max speed was 107 MPH where w/ the 335 it was always above 115. That means the E36 is that much better in the corners than the 335, even with basic suspension.
I can only imagine what it would be like with the same suspension as I had on the 335.
I thought you all should know.