I have never seen a .28 pull even near that HP. Never listen to numbers given by the company. Cars, motorcycles, rc engines and so on, they give you a certain hp number then you dyno it and not the same, not even close. This list is from this site with hp numbers on a dyno. Hope this helps.
I never pay too much attention to HP numbers but for those who really cares... It's a bit old but a good reference
Issue # Company Engine Size (ci) Ave. HP Ave. TQ Low (HP/TQ) Top (HP/TQ) Corr. Factor Peak HP Peak Torque Peak RPM Price
111 O.S. 12 TR 0.120 - - - - - 0.65 @ 30,000 rpm 25.00 oz-in @ 23,250 rpm 39,350 rpm $130
111 Trinity 427 Monster HP 0.260 - - - - - 1.02 @ 24,250 rpm 48.00 oz-in @ 19,250 rpm 38,100 rpm -
112 Mugen Seiki X12 SE 0.120 - - - - - 0.88 @ 21,500 rpm 28.80 oz-in @ 30,000 rpm 42,500 rpm $290
112 O.S. 12 TR-T Outlaw 0.120 - - - - - 0.73 @ 31,500 rpm 25.96 oz-in @ 27,250 rpm 41,000 rpm $160
112 O.S. VZ-B V-Spec 0.210 - - - - - 1.47 @ 24,250 rpm 61.20 oz-in @ 22,500 rpm 41,500 rpm $320
112 RB Concept V12 Rody 3T 0.120 - - - - - 0.95 @ 34,250 rpm 28.80 oz-in @ 28,750 rpm 44,750 rpm $375
112 Rex R12S5 Outlaw 0.120 - - - - - 0.84 @ 34,750 rpm 26.88 oz-in @ 26,750 rpm 41,250 rpm $385
112 Rex ReR5 5-port turbo 0.120 - - - - - 0.84 @ 34,750 rpm 27.00 oz-in @ 26,750 rpm 41,250 rpm $320