Its real and works on smaller engines, you might need 2 for a 250. ONLY $2500 ea.
x1.https://www.youtube.com/watch?v=7a_J2X88fSE
X2..https://www.youtube.com/watch?v=_yrxbcB4CwA
x1.https://www.youtube.com/watch?v=7a_J2X88fSE
X2..https://www.youtube.com/watch?v=_yrxbcB4CwA