Just thinking outloud here and please do correct me if i am wrong. Our supercharger are posive displacement so the air flow is fixed based on supercherger rpm and displacemnt. I can see a defective or worn out supercharger increasing cfm when rebuild or clearances tightened up.I don't know what the oem specs are but i am sure it's very small gaps maybe.0005" to .001" so not much air can leak by.You also have to keep in mind that the centripical forces increase as rpms increase so the rotor grows and tightens that way also. I expect that you may see some improvment over 20 psi vs stock. As far as ported heads and other clean up i expect that is where most of your new power will come from. a rebuilt super charger, ported heads and other stuff reworked for 3200.00 not to bad as far as cost. however $3200.00 could have bought a nice turbo or a eaton 1900 tvs.