My 1st mod was going to be new wheels. I took off the stock 19" (staggered) wheels, took pictures and listed them on craigslist, sold for $1100 which is very cheap for stock chrome wheels which are known to be very rare for these cars.
New wheels i was buying were the style 128 factory BMW 21" (staggered) wheels.
I found a very good deal online for brand new chrome wheels with tires. $3,000 for Brand new wheels and tires.
If im not mistaking the 21" wheels will run about 4K+ at the BMW dealer. Wheels for me are a must because they make a world of a difference on the car. It will change the appearance on the car dramatically.