GMS unit wont do the normal S10 owner a thing, not even with a Bill Mach reflash, it cant!!! Oh I know some non S/C owners will say it does but the butt dyno ideal comes to mind very fast.
First off, PRO-M had made what GMS called the "C" units , which were calibrated to give the same reading for the same air flow numbers as stock did. They knew air was gonna pass beyond the wires unseen so they flow tested them to then match the stock reading per flow. GMS took it upon themselves to get a bunch of A/C Delco stock units, cut the plastic center bar supporting the wires and then add oversized ends to them which PRO-M had also made. They called the calibrated true MAF a "C" and the modified overpriced stock ones NON. The got caught by Pro-M and Pro-M pulled there making and support to GMS forever. WHo makes them for GMS now??? GOod question since there arent that many out there who make them. So on that fact alone I would avoid GMS's all together, track record shows they like to run on false premises. Thisat one time was posted on Pro-M's web site.
Now Pro-M still makes and sells the real units. But your stock one can handle everything you can throw at it correctly till around 250-275 flywheel. You can bolt on every mod out there NA and not hit those numbers. Add a cam , head work etc and you may just hit it. Pro-M makes these units for those who can get beyond the 275 barrier where CFM flow rates are over what the stock one can handle.
You want to know another thing. You know why all the aftermarket CAI kits have elbows in the front? K&N knows , but I bet to guess the other dont and are copycating. It does 2 things, one is it puts the larger filter area near the headlight bucket hole for cooler air. Second when air travles in the tube, air changes speed, the inside turn will go faster than the outside turn, air will tend to travel the shortest path. Well when it enters the MAF , most of the air passes under the wire, unseen. Well when the MAF reports lower air flows it adds timing. The gain you get is not all from more air flow, its part due to more timing. What helps it further is the cone shape, a cone shape causes a vortex to be created, larger volumes of air in a tighter space, thats why the cone narrows towards the very front edge, if it didnt, no vortex. Now GM made the stock air box to flow straight into the MAF so it could see most all the air and not have this imbalance, the screen and center bar are there to correct problems in flow, not restrict even though it will.
Save your money!!! The CAI is adding timing for you, helping aid in the motor getting all the air it can, having a larger MAF area when the throttle body is smaller, and think about that, the throttle body bore almost dead matches the stock MAF size, the throttle bore becomes the restriction point, what do you do then??? Bore it out and slow the velocity of air entering!!!