Unfortunately, your kind of screwed if you are playing through a high gain amplifier. What tends to happen is when you put an overdrive pedal in front of your amp to boost your volume, it just adds more gain.
I wanted to buy a pedal to boost the volume on the crunch channel on my 5150 combo, because I was never really happy with the lead channel tone out of that amp. Anyway, I was really excited to see the new Seymour Duncan Pickup Booster pedal because it was supposed to bump up the volume of the input signal without affecting the tone. I tried it on the clean side, and it worked as advertised, but when I put it on crunch, it merely added more gain, and did little to boost the volume.
The best thing I've seen is the Mesa amps that have a "Lead" button on the footswitch. It basically is a switch that toggles between two different volume knobs on the same channel. Works slick as ****.