i do agree with mikeski about the zapco costing a little bit more... they are reasonably priced on the used market imo..
however they do offer more than just reliable high power and when you add everything up the cost is just about the same or a smige more...
here are some reasons to consider zapco with symbilink options:
-built in line drivers (increase the line voltage to 6d to 12 db (12v if i remember correctly)
-balanced operation (no alternator hum/hiss...very quiet...this is needed due the most systems are horn based and the amps are generally run "wide open'
controllers - you can add a symbilink volume control to the amp and keep your interconnects as short as possible.
by eliminating long interconnects and additional line drivers you save alot of install time and some money (you will need a symbilnk volume control about $40)
the nice thing is you have a balanced, well enginered system rather than trial / error one...i have never heard anyone regret installing one once they see, operate, and hear one..