I have alot of experience with the BMI TC3 on foams on ashfelt in modified. I have won numerous races and championships with the following setup.
30 or 35shore hardness tires front and rear, 26mm wide.
40wt oil rear, # 2 pistons,springs to suit track (red /copper/silver)
50wt oil front, # 2 pistons, springs to suit track (red /copper/silver)
Shock tops, mid position
Shock bottoms, wide position
Camber 1.5 degrees all round
Losi 6 degree front caster blocks/hubs
ride height 5mm all round
Thats about all I can remember off the top of my head. The most important part is the 6 degree caster blocks or you cannot get around fast sweeping corners with enough speed.
Also if you can use the 30 shore tires (rear 30's for the rear and front 30's for the front) then you will hold more speed over the course of your run than the harder tires that everyone seems to have talked about so far. This is not carpet, you need softer tires.
This is a set up for untreated ashfelt.
If you need to know more then get back to me.
Team Tekin www.teamtekin.com
B-Fast R/C Performance www.bfastrc.com
Ryper Hobbies www.ryperhobbies.com.au