ok I understand that part of it. BUt Im still having trouble understanding why you need a dyno tune. ISnt that what the maf meter and o2 sensors do, is tell the ecu is its running to rich or lean and compensate time to ajust for that? If thats so then why would it matter if you have boost? I just seen a gsr with a stock engine and head running 9 lbs at 325 whp, it was tuned tho so I dont get why an untuned stock gsr would not have somewhere around 275 whp untuned?