i was wondering if anyone knew if i should use the s4 or s5 racing beat aluminum flywheel if i have a s4 engine and s5 tranny. what is the difference between them, and which counterweight should i use (if they are different)

 

I beleive the racing beat lightweight flywheel has the counterweight included in it

so you must by he one that fits your serie

 

Exactly, the flywheels are exactly the same; it's the counter weight that is different. In you case, you need the S4 counter weight.