yo - superdoopercooper... some comments for you..... I hope you find them helpful...
Why do you want to triple your subs? Are you lacking sound quality that you desire - or you just want to produce more "boom boom"...??
First - my opinion - prolly not. You are likely to burn up your amp if you wire the subs incorrectly. IMHO - you would get more big and better sound with higher quiality components. Seems you are outgrowing pioneer
(not a bad thing)....
Secondly, if you plan on running 1000+ watts HELL YES. You will want an additional battery, a battery isolator - and maybe even a CAP to help with instantaneous power demand. You will need to upgrade your altinator to have the amperage requred to run the additional gear. You run the audio off the "spare" battery - the isolator will help you with that. In this configuration - you can run the battery dead in the parking lot - but still start the care normally (very desireable)....
Third - your amp is a 1/2/3 channel amp. This means you can run 1 speaker MONO. 2 Speakers STERO, or you can run 2 speakers STERO and SIMULTANEOUSLY run a SUB.
I cannot answer the wiring question until you list the resistance of the new subs you will be buying... this will make a BIG difference.
If the subs are 4 Ohm, you can run them in parallel safely (6 Ohms)... BUT, if the are 2 Ohm subs, you will burn up your amp if you wire parallel (3 Ohms and your amp is only stable to four)....
So - if the subs are 4 Ohm, you cant mess up. Hook all the positive wires together, and connect them to the positive lead of the amp, hook all the negative wires together, and connect them to the negative lead of the amp. This will connect 3 4Ohm subs safely to a 4 Ohm stable amp.
If the subs are 2 Ohm, you will need to SERIES 2, then parallel the 3rd. This will not sound balanced (the series subs will be lower volume at the same power)... This is not optimal but will keep your amp from burnging up.
Speaker 1 Positive lead to amp, negative lead to positive of Speaker 2, negative lead of Speaker 2 to negative lead on AMP. Speaker 3 hooks up normally (positive lead to postive amp, negative lead to negative on AMP)...
WHEW..... you hit a lot of topics... hope this book helped some LOL