[R170ybugly........]

What's the deal with these are they accurate on operation as far as the ecu goes reading the boost all the time or just for a cheaper clutch replacement..

 

[kenhewitt]

The objective is to increase air volume/flow. Bolting on a smaller pulley ideally needs a remap as well. Have a look at this site on ebay, might be useful,

ibf-auto