Snyder's Motorsports used to have a dyno graph on their website of a Blaster . Stock, +2, +4, +6*. Best results were +4. Very nice increase in mid-range with little loss at max rpm.
While jetting would not need changing, it would be more susceptible to detonation if you were jetted towards the lean side. Higher compression would also need to be watched for deto when advanced. Though unless really high and cheap gas this shouldn't be a problem.
