Im running the XE275Hl with exhaust manifolds. Nice cam with good power. I had to use adjustable rockers because the ramps were very aggressive. According to Andyf keep duration lower than 245 at.050 because the torque curve will fall out of bed with the manifolds!!!Take a look at his articles.
http://www.compcams.com/Community/Articles/Details.asp?ID=2004264609