[quote=flu]Don’t plan on doing any sort of competitive class racing. I guess I just want to get on the track and just…drive…. Right now, the only thing I have is a stripped 2250 lb miata that with an Eaton MP-62 supercharger on the cold side. Supposedly, it’s suppose to be about 200hp at the wheel, which is more than enough for my current skill level.[/quote] As with all things ‘under pressure’, depends upon what the boost is and your inlet temperature. Of course CARB can step in and limit what you can do.
[quote=flu]And I’m running slightly larger tires 225/50/15 or 245/45/15 on 8″ rims (yeah, I know stock miatas are 14″) only because tire selection on 15″ are much better than 14″. Running slightly aggressive streetable pads: Hawk HP+ on stock calipers and rotors, which is fine for auto-x, and I don’t mind switching if it’s needed (I haven’t found a need to yet).[/quote]For tracks, you might want to see if you can get a larger rotor. With the larger rims, you get more space for larger rotors. In Autocross, you don’t get up to very high speeds. Tracking at something like Willow Springs, you will get to much higher speeds. Double the speed of a vehicle, you are dealing with 4x the energy. The larger diameter can help the ride, it will allow a lower profile, though at 245 in width, the tire may limit top speed (rolling drag can increase with width on the tire – part of why true off road tires are detrimental to gas mileage) With your lightening, you may want to check where the center of mass is in the vehicle(or weight distribution). A car that will not push in Autocross(understeer), might push on track use at a higher speed. You can relocate some weight to the back via the battery – heavier if needed. If you are not using the AC and don’t plan to use it – might as well remove it. It will also help with cooling the engine when the condenser is removed.

I think you can do a full cage w/o a hardtop. BTW cages are much stronger than just a hardtop (that is a properly built cage). Most cages are Chrome-Moly, sheet metal that makes up a hard-top, is not Chrome-Moly (and doesn’t do as well when a car rolls). Another thing to look at is putting reinforcement bars within the doors of the vehicle (protect the driver if T-boned).

[quote=flu]As far as “twitchy cars”, that’s one of the reasons why I like the miata.[/quote]The problem is that when you go from Autocross to tracking, your speeds change and the speed at which a car can change direction contrary to your intended direction also increase. You are probably running some camber in the miata right now, adding in a little more castor might help reduce twichiness at high speeds. As a side note, it would definitely be better to use a car that is not a PITA to fix. You may also want to look at oil pans that hold oil better on a sustained corner (corners last one or two seconds in autocross), track corners can cause the oil pickup to start drawing air. Another trick to use is to run a car about 1/4 of a quart above the top line (separation between lines is about 1 quart).