I've never heard decent BASS from a 4X6. The shape is all wrong for accurate sound reproduction. The tweeters fire into the window and produce inaccurate imaging. They just all around SUCK! If you want them to fit nice get Pioneer Slim Line coaxiles. They are very shallow and have tiny magnets. I'd install a 150 megahertz 12 DB per octave passive cross-over from RadioShack (Bass Blockers). They should be like 1 buck a piece. Or, if you don't feel like trying to figure out what value capacitor that is, just shell out the 10 bucks and get them from an audio shop. I blew my Pioneers ($45.00) in about 5 minuts because I didn't have bass blockers. Plates would be a much better investment and more worth the hassel of getting them into the dash. A 4 inch mid and a nice tweet mounted next to it. If you want any kind of REAL sound up front you will have to install 6 1/2 's in the doors or kick pods. I have 2 6 1/2 's in each door and 2 where each 6X9 and ash tray used to be (8 total). My Sony Explode goes through a Pioneer 9 band parametric EQ and into a 50X4 to give each 6 1/2 a clean 25 watts RMS with a high pass of 100 megahertz at 24 db per octave. Head power drives Motorola horns next to 2 Power Acoustic tweets in homemade 4X6 plates in the dash. It was all very cheap to do, it just took a little time and imagination!