I'm installing a typical coil over sleeve on the bilstein shocks on my 01. The perches and springs are the normal stuff that you usually see on every other IT prepped Miata. Mike @ ISC mentioned to me that I should install an extra washer (that I would need to fab) because I am running stock NB top hats. I wasn't sure what he meant, but figured I'd be able to search it out. Well, I've searched around, but couldn't find any good info on this. Anyone help me out? Do I need to fab a washer to go between the new spring and NB hat? FWIW, my front springs are pretty big -- 800 lb. Are OE hats weak with big @ss springs?

New hats aren't an option right now. You don't need to convince me to go to a spherical mount; I already understand why it's better than the stock hat with rubber bushing. I want to road race but still get 1 more GRM challenge out of the car, so I can't spend real money for real suspension now. Maybe next year it can have real suspension.

 

I answered this for myself today. I'm installing a cheap coilover sleeve kit with 2.5" ID springs. The part labeled "bumpstop support" in the picture below does not fit inside the small diameter aftermarket springs, so it has to be replaced with a washer that has <2.5" OD. It's needed to trap the tophat on the shock rod. It wasn't included with my kit. I guess the more common Ground Control kits include that washer, as I didn't find mention of it anywhere.