2+2's Lead Guitar Players, Help Please.

[IQ89]

About 2 years ago I bought Fender's cheapest Strat ($400), I haven't changed the pickups yet, not sure what to buy. Then, about a year ago I bought a 20 watt Marshall Valvestate 2000 practice amp. It has a pre amp (10 inch celestion speaker), and it's more than loud enough for playing in a bedroom.



I also have a Boss MT-2 Metal Zone pedal.



..and an old DOD Stereo Chorus FX65



Okay, together they sound really good for chords; to get a Van halen type of sound, but here's the problem: When I play individual lead notes it has a Boxy sound that I hate. The sound reminds me of Brian May's Vox amp. It doesn't sound that way with just the amp alone, but I don't really care for that sound either (the sound is almost there, just needs a little something [maybe 30 more watts of power?]), Is there some pedal effect that you could recommend that might give it a decent sound? Or am I just going to have to get a 50 watt combo amp w/a 12" speaker?

Guitar player's sound that I like:

Eddie
Eric Johnson
Jeff Beck
Yngwie
Steve Stevens

Thanks for any help