well I don't know what kinds of effects you have on those pedals but if you want to sound heavy crank the treble all the way up, the middle all the way down, the bass all the way up, the gain all the way up, and select to use a bridge humbucker if you have one. also turn the volume knob(s) on your guitar all the way up. this will provide probably the heaviest sound possible. now i am well aware that I am going to get all kinds of replys with people yelling at me telling me that this is a bad idea but I'm just saying this is how achieve the heaviest sound possible without buying anything else. do either of your pedals have distortion or overdrive? if not then does your amp? if not then you really should consider buying a distortion or overdrive pedal... you could probably find a real cheap one for less then $50 (us). also if your pedals have compression, sustain, or shifter, they'll add to the heaviness. hope this helped some!