Some people think that angle plug heads produce more power than straight plug heads. This common misconception is not true! In reality, the ONLY benefit to angled plug heads is to provide more spark plug boot clearance with some header designs.
The idea of these designs producing more power came from some early angle designs that placed the plug location closer to the exhaust valve. This WILL create more power, but straight plug designs that have since been moved in the same fashion produce the same power.
BluePrint Engines offers both straight and angle plug design heads – your choice should be based on appearance and cost – not on one being more powerful than the other. 
– Tech Tip courtesy of BluePrint Engines
