yeah, is 3 stage, normally it come wif cvt b/box (manual ori ek3 is super hard to find). u can either mate wif ef (cable) or eg/ek (Hydroulic) manual g/box.
Last time my chasis need to cut n ketuk due to auto g/box coz auto g/box is bigger than manual. If u swap in d manual g/box at d first place then no need to cut, ngam2 go in. I'd also regret bcoz didin swap in d manual g/box first.
My advice, go for D15B Vtec from EG series instead of 3-Stage EK3 bcoz D15B Vtec EG is more on performance while EK3 is combination between economy n performance. But who care bout fuel economy if u wanna go fast...

If manual D15B Vtec in 2nd gen, those EG wif stock b16a will find face hard time wif u. My fren D15B Vtec in 1st gen can tapau those EF/EG wif B16A..
Btw, if D15B 3-stage vtec convert to manual, d problem u facing later on is d ecu. EK3 manual ecu also super rare to find one. In-order to utilize d true power from d manual g/box, u need to find manual ecu. So u need to convert d ODB-2A to ODB-1 wiring (which mean EG series).
Anyway, i'd oledi sold my car oledi last year to awner from JB. Thanks.... I miss my car....