Man.....
There are legal Intercoolers out there or as a matter of fact they're legal if you're running stock Air intake box, also don't cut holes for the cooler piping.
If you'd like to keep the Mine's ecu, at least get an SAFC to either en-rich or lean your A/F out, make sure it runs abit rich just to be safe. I did have a Jap Chipped ECU, nothing much really beside from letting you rev pass the limit and speed limit (this was fun watching your speedo arm going pass 180 and going back to 0 again)
Check your diff, rip a small burnout (in a control enviroment) to see if you still get 2 decent black lines at least then you'll know its still good.
When you're back at Heathcote, lower your tires pressure to at least 20psi, rip a decent burnt out and see how you go. If that still doesn't help then try to ride the clutch a bit but by doing this you'll cook it in no time.
I reckon with a decent cooler, SAFC tuned with current mods that you've got, you should be able to run at least a 13 flat or high 12.
Good luck and spray your front bar and side skirt to match will ya, if i was a cop, i'd pull you over just for that .