You're trying to argue over a quantitative point by raising somewhat qualitative (ie. "install" - obviously a car with Zapco amps and shitty frequency response will sound worse than a car with Boss amps and pleasing frequency response) points. Again, car audio is not an environment conducive to comparing the sonic signatures of amps (such as frequency response, and different impedances with tube amps (why some think tube amps have a different sound)). Again, I'm confident that I could hear a difference between Cary monoblocks with a BAT preamp and a Sony receiver with no processing difference.
Edit - I didn't read your other posts before I posted that as I was watching TV. Why would say, different capacitors in the Brax change the sound so drastically? Unless the Lanzar was using completely crappy internals, there is probably an almost immeasurable difference. For the record, the most expensive amp I own (well it's on its way) is a Genesis Dual Mono which I purchased for just over $300 used. In Atlanta, the "high-end" is JL amps sold by salesmen preaching how JL subs are clearly the best sounding subs on the market, so I don't hear anything from salesmen. There is obviously very little difference between high end brands, but in your earlier post you compared Boss amps to Zapco amps. I would say that comparison is more drastic than a Lanzar to a Brax. RC's test, IIRC, stated that completely crappy amps can't be compared to the "high-end" amps. Some more food for thought is that many ECA members swear by dual mono amps, yet their measurable benefits are not extreme.