Ok I have a DEH-P8400 Pioneer HU. I bought the Vifa 7" mids for the front and am going to buy some tweets also. I have 2 12" subs in the back and im not sure what im going to do with the rear seat speakers. Anyway my questions are should I get a crossover, or just use the seperate outputs on the headunit? And also what does like the 3 way fronstage..and 2 way rear stage with sub mean? Does it mean that you have a stage for tweets, mids, and somethin else for the front and a tweet and mid for the back? No hard evidence of answers after searching so I figured I just ask and get a concrete answer.
Thanks,
-Matt

i dont know what the pioneer's crossover options r? i too have the vifa pl7 and neo tweets. my kenwood hu is the top model but i wouldnt run its crossover settings. i got a ppi active crossover to run my system and future expansion. check the other threads. u may be able to get passive crossovers made from madison (again check the other links).

3way=midbass,midrange, tweet
2way=mid(trying to cover midbass and midrange), tweet

frequency range is generally 20hz - 20,000hz

for now my 2 way front stage will be vifa7" 100-3500, tweet 3500-20k w/ sub 100 and below but the vifa can go lower if i want, thus lowering the sub too. adding a midbass would cover 100-250/300hz with midrange and tweet handling everything else above.