Im with you bigaudiofanat, I will say this though. I bought a base sport and I got the stock bottom of the barrel radio because I knew I was just going to rip it out anyway. I put an aftermarket radio in that is actually a china model (no namer). With that and my ipod together I am able to get some pretty amazing sound out of the factory speakers without much distortion. I can hear it all loud and clear and I am also experiencing bass that was not there with the factory head. IMHO the head unit is where the majority of your sound quality will come from. Garbage in garbage out... not too far from Microsoft mentality. Speakers can make a difference but if you have a garbage head your speakers wont matter. It looks like you have a decent pioneer HU. I had a pioneer in my 3000gt before with infinity (one of the best speakers made IMO) speakers and it sounded pretty good even without a sub. I listen to some of the same music you do. Don't know if you are playing from a CD or ipod or what. If it is from an ipod check the EQ settings on the ipod to maybe tune the sound before it gets to the head unit. Thats what I did and mine sounds great with a no name head unit and factory speaker. :-)
Oh yeah.. and I am competing with my fully open exhaust when I ride so and it still sounds good. :-P