[bNks334]

Thing I regret #1: Not trusting my gut in how I was setting my car up. I decided to try what the forum consensus is for my 135i: stiff front spring rates relative to the rear and a BIG 27mm front sway. I hated it. Sold the sway, went back to stock bar, and increased the rear spring rate from 12k to 16k to make the suspension neutral again. I also went back to stock-like F:R ground clearance bias that keeps the rear squatted a few mm lower than the front. That's what keeps the chassis balanced and the dynamic cross-weight in check.

I was just talking to a very fast driver at autocross who was ripping on the 1-series "it understeers constantly until it oversteers from power." uhhh... no... the person campaigning the car just set it up terribly (another very fast driver). Instead of a 235/275 tire setup try 255/275. Instead of running 10k front springs and a 28mm front sway with tiny front tires (for a 3400lb car) try running something more reasonable like 6k w/ M3 sway bar... My car does not understeer it actually oversteers. It's possible.

Thing #2: My custom tune. I wanted to show what the stock turbo can do so we maxed it out on E30. Hitting 23-24psi and making 500wtq is fun on the street, but the power is not very useful at autocross/roadcourse (I was spinning in 3rd gear on track with rcomps). I plan to re-tune the car on as much ethanol as possible while keeping boost lower at like 16-17psi peak. That will keep the low rpm torque down and hopefully pick up some top-end power. Should make for an easier to drive car with a better power curve.

Thing #3: For the way I use my car, I wish I had gone with stiffer bushings everywhere. I went for cheaper instead. specifically, stiffer engine mounts would be nice since the 034 mounts I have don't come close to being aggressive enough to match poly trans mounts and RSFB. Also, forget doing a diff lockdown bracket and upgrade the differential bushings themselves. You DONT want your differential locked in place if you have soft bushings elsewhere... you need the compliance...