[Trueoo7]

I took a 4" handheld grinder to mine. Get some disks, 60 or 80 grit and take a little off the flared base each time. Took me about 1 1/2 hours to get it where I wanted it. Thats not all grinding..... putting it on and taking it off eats up a lot of time. Be sure to where safety glasses because bits of aluminum can get caught on the disk and then be thrown off later. Its definetly worth the aggravation and if you screw up and take off too much you can buy just the base plate from mustangsunlimited.com.
Good luck!