i wouldnt buy a c&l meter. it uses your stock meter and uses sample tubes to give the meter the proper calibration. the pro-m replaces everything. i have also heard of people having driveability issues with both the c&l meters and the pro-m 75mm. as the saying goes, you get what you pay for. i got my pro-m 77 shorty off of the corral classifieds for $165 shipped. you may want to take a look over there.