Baron Power Pulley

It certainly can make a difference with speed depending on how you configure your setup. Just remember your bicycle - bigger front sprocket and/or smaller rear sprocket = faster top speed at the cost of acceleration. Smaller front sprocket and/or bigger rear sprocket = faster acceleration at the cost of top speed. The same concept applies here. With regard to vibration, it's really hard to say. It depends on where in the RPM range you're experiencing that vibration and then trying to figure out where you need to be to minimize that. Maybe play around with your bike to figure out where you need to be in the rev range in order to get the best performance / vibration setup.