[SDJASON]

So, im the proud new owner of a 2005 Scion TC Silver

I absolutely love the car, and actually, its got a pretty decent stock sound system, compared to my last car, a 1995 Saturn SC2 with 4 blown speakers..... :-P

Anyways, I've got the following equipment leftover from my SC2:

-4x Pioneer TS-A631P 6.5 inch Round 3 Way Speakers
-1x AudioVox Prestige PAB-450R 400W 4 channel Amp
-1x Alpine V-Power MRP-F200 Amplifier 4x75W Amp
-1x Random Aftermarket JVC Deck with 4 channel RCA Outputs
-2x Crappy Horrible 12" Cuspid Subwoofers

When i set up my old car, my plan was to use these parts and set up the wiring and everything correct first, then upgrade each component as money came in (it never did) I had 4x RCA from the head unit going to both amp's in the trunk via splitters, then high grade speaker wire running from the Apline to all 4 pioneer speakers, the Crappy Sub's were powered by the Audiovox Amp.... It gave "decent" sound, which was all i ever wanted... and since i never got the $$$ to upgrade the components, decent was fine

Now however, im looking for a "more than decent" setup.... however the one caveat is I no longer care about earsplitting bass, and id rather not fill my trunk up with unnecessary subs....

My first question is, if i were to replace the stock speakers with my Pioneer TS-A631P's (with Alpine's adapters) would i get any significant sound quality increase while still using the stock head unit?? I've heard the stock head unit has custom EQ settings to aid the stock speakers... will these EQ settings be detrimental to my aftermarket speakers in terms of sound quality?? Is there a way to disable or turn off these custom EQ settings??

Assuming i wanted to stick with the Stock Head Unit..(I've invested in the Sattelite Radio to RCA adapter to pair with my DP1US IPOD interface) would i get any benefit from wiring the speaker's to run off the Audiovox Prestige Amp (the admittedly better of the two amp's i have) or would it be better to leave it as is...

Once again, im not looking for the best of the best, just above stock, so my final question is, will any of the things ive suggested above give me noticeable difference over the stock system, or should i try something else? or not even waste my time??

THank's a LOT for your reply!!

~Jason