crossover freq points?

Hello,

I was wondering if I could get some advice from the pros out there on setting up my crossover points.  My car is a 2001 chevy malibu. 

First a little info on my setup.  I have a IVA W205 running two JL audio amps, a 1000/1 running two alpine TYPE R 12's and a 300/4 running the older style kicker resolution R5c midrange and R25a tweeter with the kicker crossovers. 

In the near future I want to use the rear channels of the 300/4 to run a Kicker CVT65 6.5 inch sub which I am going to put up front in a small area under the dash in the middle of the car and build a small box for it.  My goal is to use this small sub for my midbass driver and have it give the "illusion" of up front bass as the two 12's are in the trunk.  If you aren't familiar with the slash amps they have pretty nice built in crossovers with selectable slops, a multiplier, the 1000/1 has a sub sonic cutoff. 

I would like to get some advice on the crossover points for the subs, midbass, and components, and should I use 12db or 24db slopes? Do I need to have some overlap in the frequencies?  I know this is a complicated question but I really want to get everything set up porperly. 

Thanks in advance for any suggestions.

No, running two sets is never the way to go.  You should be able to mod the 6.5's into place in those openings.  The few Hz extra they provide will be welcome at the 80 Hz crossover point with the sub.

Modding the door's inner panel is easier than cutting the sheet metal to fit the back of the speaker through, but do one or the other.  And be sure to use plenty of damping on all sheet metal surfaces in the door...ultra important for that 60 to 100 Hz range.