per SPR's website
Ultimate TBI Overhaul of your unit which includes boring
This is the most comprehensive rebuild of your GM Rochester 220 TBI unit. Here we will degrease, glass-bead blast, bush shaft with oil impregnated bronze bushings, new IAC, new TPS, set TPS voltage to .550V, IAC gasket, new spring and diaphragm, make regulator cover adjustable, complete servicing/testing of injectors and installing new filters and o-rings, raise injector pod to 1/4" (SBC), thin shaft, shave air horns (SBC). Includes custom cut base flange gasket, air cleaner gasket and fuel line o-rings. We will also bore your unit to 46mm (SBC) or 54mm (BBC) and install custom fit blades.
driveablity, It idles better, the acceleration is smoother throughout the powerband. Before I had it rebuilt/bored, power would seem to fall off in certain areas of rpm while accelerating, I dont have those issues any more.