MB Quart are pretty bright (too much / too sharp high frequency). That's because of the metallic tweeters. There are some options to deal with that though. First, get a different brand that uses silk tweeters, they are MUCH softer (like Eclipse). Second, aim the tweeters into the passenger compartment as opposed to reflecting them off the windshield (the windshield makes them harsher). Third, MB Quart crossovers have tweeter settings that allow you to tone them down, to a max of -6 db.
I'm going to try installing my older MB Quart Q series this week sometime. I have the Infinity system with amp, so I'm going to try installing in place of the stock speakers without the crossover, since the amp has separate outputs for the door speakers and tweeters (it would be very tricky to properly use the crossovers with the Infinity amp). Unfortunately, the Infinity system seems to crossover at around 4khz, whereas the MB Quarts prefer around 2khz.