ashrs

hi all right i'm going to be buying a pro-ramair induction kit for my s2 only prob is that my s2 has got a t34 on it so that means that i can not just order a standerd s2 one so my options are 2wd cosworth,4wd cosworth,t34 escort cosworth,rs500 but most of s2 in fastford/performance ford that i have red about with big air filters in them are rs500 i was going to order the t34 esort cosworth one but not to sure what the differnece is between theis filter are so can some one help me please