i'll jump in rocky,
i had an 85 DT175 that i loved and as it was only a hack bike, fell victim to some experimentation. i gutted the stock pipe as they're heavilly restricted with baffles on the inside, fitted a smaller mx style silencer, cut huge holes through the airbox, jacked up the arse end by welding a spacer to the top shock mount, fitted some heavy duty fork springs that came from god knows where but they worked. on trail rides it was just so much fun, good clean trailie power, low to the ground, so was easy to manouver. my only real gripe was the gearbox ratios. i think i ran a real small front sprocket too.
have fun with it man!