Whats the big difference between type R b18 pistons and regular b18 pistons

Is it the divit in the top ?

Im buying a b18 for my rex and it comes with (type-R) Water pump oil pump and pistons but my main concern is the pistons

any responses are appreciated

 

Please remember there are several B18's LS, GSR & ITR then to further muddy the water there is USDM and JDM so there is no "regular" B18.

USDM LS has -3.20CC dome
USDM GSR has -0.60CC dome
USDM ITR has 3.64CC done

 

It basically means your motor have high-compression. Your main concern is going to be the need to run premium fuel only (91 octane). If you don't run 91 octane, the best thing that will happen is your computer retard your ignition timing & you won't make max power (if you have knock sensor). The worst case would be damaging the motor from detonation if you don't have a knock sensor...