believe it or not, the M271 200kompressor engine has around 200hp, which is alot for this car. the old 180 & 200kompressor engines were garbage, but the new one is always underrated.
if it is a V6 then it is a 240, 280, 320 or 350. either way, a picture of the engine would allow me to tell you the exact one. and if you want me to pull the specs of this car all you have to do is PM me the chassis number (17 digit code which starts out WDB203)
as for mods, trying to make a C55 replica in PK is not worth it. roads suck and getting all the right parts will be impossible. if you leave even on part out you'll be stuck with a lemon. my advice is to stick with what you have.