After working a lot of O.T., I finally have enough money to get one of these coilover. This is for my ITR. This car is mostly for autox and a little street if the weather is good. Please pick one and why? thanx in advance

 

tein flex or RA

 

Flex FTW

 

I think the fightex come with 8k (448lb/in) front and 6k(336lb/in) rear? That doesn't impress me much because higher front rates than the rear will bias towards understeer.
That will feel cushy on your daily (how compliant a ride feels is weighted on the rear rates), but you make emphasis on more auto-x than anything, and you want to inprove turn-in and reduce understeer.
The fightex cost about $2300-$3000?
You could outfit yourself with custom rate eibach ERS springs or hypercoil both of which are tried and true in many sanctions of racing such as nascar, cart, scca, nasa, etc, paired along with Koni 3011/12 dampers which are rebound and bump adjustable.

Out of thsoe two, if you are set on only those two, I'd choose the one with the most flexibilty in changing spring rates, and the easibilty of getting them revalved incase any one of them needs it. Also things to consider are the damping characteristics themselves, such as their highspeed/lowspeed bump and rebound damping, and how easy the adjustments are, and whether the adjustments really have an effect on teh damping curves.