That's complete BS! How many engines have you dyno tested with these cams? I've dyno'd around 10 engines of various brands using all three sizes of Thumpr cams and every time they made more power than expected and by no means did they underachieve.
Not only do they sound good, but most times there is a solid 2000rpm between peak TQ and peak HP. Very wide power band.
Brian
A question, Brian: Do the Thumper lines run best installed as per cam card,or are you adding/retarding on the intake center line installation point? Was just curious,of course this is completely affected by intake/exhaust flow...(?)