1998 Plymouth Neon Expresso, system

Hopefully this is a good place to post this question. From the lurking I've done, everyone but myself seems very knowledgeable haha. I have a 1998 Plymouth Neon Expresso in which I've put in aftermarket sound equipment. Head Unit: Pioneer DEH-P3700MP (2 pair pre-outs, 2V, 22W x 4 RMS) Dash Speakers: 3.5" Rockford Fosgate P132Cs, 15W RMS / 30W Peak (400Hz bass blockers installed) Door Speakers: 6.5" RF T162Cs, 75W RMS / 150W Peak Rear Deck Speakers: RF T1693Cs, 110W RMS / 220W Peak Subwoofer: RFP 3410 10" paired to a P160.2 Amp. Speaker is 200W RMS / 400W Peak, Amp outputs 160 RMS 236W Peak So here's my question - the Pioneer deck says it should be hooked up to 4 Ohm or 8 Ohm speakers, but right now to avoid the factory built-in crossover, I have the Dash and Door speakers wired in parallel (2 Ohms). Supposedly this is a bad thing, so I was looking to get an Amplifier for them. After emailed RF support with the idea of a P450.4 for the Door/Deck speakers and simply running the Dash off the Head Unit still, they responded that I should use a P4004 and wire the Dash/Door speakers in parallel. My questions are: Why the P4004 over the 450.4? 4004 is 50x4 RMS @ 4 Ohms and 100x4 @ 2 Ohms, the 450.4 is 60x4 @ 4 Ohms and 110x4 @ 2 Ohms. Don't both of these solutions end up with way too much power going to the Dash speakers? Remember they can only handle 15RMS, yet even with the P4004, wouldn't they be receiving 100W at full volume? If someone could please clarify this situation for me I'd greatly appreciate it. As well as whether there is anything inherently 'wrong' with wiring the four 'main' speakers to the amp and leaving the 3.5"s running off the front output of the Pioneer deck. Thank you

Your idea is the way I would go about it.  But I probably wouldn't use those dash speakers at all;  just run the four speakers off the 4channel amp and let the head unit be just a preamp, not an amp.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Well - I paid to have those 3.5"s installed since it took some modification to make them fit, so I don't want to throw that money away. ;) Will I be causing myself problems however in trying to balance the output from the amp versus the head unit given the massive wattage difference? (22 max versus 60 max) How would I go about making sure that the 3.5"s weren't just drowned out, and WOULD they blow if I just wired them in parallel with the 6.5"s? (110RMS @ 2 ohms is the P450.4's output again) -Jason

No they may not, you will however need to a add a passive crossover to the 3.5" speakers and shut the bass of that is going into them up around the 800hz mark. This is going to take alot of the damaging energy out of that speaker as the volume starts to come up. Top Secret, I can tell you but then my wife will kill me.

Problem solved, hehe. I just went to BB today and purchased the P450.4 and had it installed to the 6.5"s and 6x9"s Rated for 60Wx4 @ 4Ohms...birthsheet says it was tested at 103W RMS x4 @ 4 Ohms, lol. I simply left the 3.5" connected to the front outs of the HU. Thank you to all who replied. :)