You drive a big boat too, eh
? I just switched my Cougars stereo system over to my Marquis. A cheap and simple Legacy amp (500 watts) with an external crossover and an entry line Kenwood deck. That said, I get AMAZING pounding (but still not competition level) from the one 12" phoenix gold sub, in a MONSTER box with one port. It barely fits between the sides of the trunk (at the bottom), and has about 1.5' square sides on it. I believe it is the size of the box that makes it work so well. I have factory Premium sound, and have left the speakers alone.
Since you are in Thunder bay, the prices will make sense to you. From KitchenerWaterloo Surplus, I bought my amp for $130, and the crossover for $30. Both are Legacy brand, and I am more than happy with them. The local stero store wanted over $400 for a 500 watt Pioneer amp, but it had a built in crossover. A word of caution on built in crossovers - most manufacturers haven't perfected it, and they don't work as well as getting an external one. A good site you should visit for you audio needs:
www.caraudioforum.com
Enjoy, and Good Luck - Merc.