Investing in a multi-effects processor much like the RP80 that juijitsu mentioned would probably be very beneficial to you. I have one as a little practice tool and they're great for just about everything... they even have an expression pedal... But to get a "shred sound" (everyones idea on a shred sound may be different...) I dial in a Mesa Rectifier model... gives you a good biting clear highs and distorted lows type sound. I crank up the compression... and add a touch of quick delay to make it sound like it's sustaining a layering a little be more.... It gives a nice full tone that allows you to play up and down the neck. I usually play with my vintage Strat in the Neck/Middle position for leads... with my middle tone knob turned all the way to one.... and my neck tone knob turned all the way to 10... this allows me to get the fullest sound possible... with a real thick sound but you can still hear the high notes over everything... It's almost like two guitars playing at once... one bassy and one trebely.