I've just got back from a ride on the big bore build, it's a monster. I really could not be happier, THANK YOU!!!!!

This is not engine, this is ART! And yes, it's worth every cent. It's not only the price, it's also the Speed And Science attitude and post sales.

Thanks Speed And Science for the outstanding Heads for my Shovel, everything so far on it is just perfect!

Piece of art!! The shape of the intake and exhaust ports are perfect. Proud to be a dealer of Speed And Science products in the Netherlands.

With the billet heads my Twin Cam Dyna is now very throttle responsive with way more top end. Thank you!!

Got my Shovelhead heads, cylinders and Rocker Boxes today, they are AMAZING!!

I’ve been working on Harley-Davidson engines about 40 years. I bought Speed And Science set of Shovelhead cylinders heads and rocker boxes - some of the best work I’ve ever seen!!!

Very impressed with the Speed And Science Shovel heads and cylinders. Much admiration from every one.

I got the Speed And Science heads and cylinders in Japan. Super nice, thanks!

I'm so impressed with the Speed And Science billet aluminum heads and cylinders, they're AWESOME!