I have the SOS kit. I was having similar issues and ended up going with their return style kit and fixed my problem. Although it's expensive and not ideal they recommend the kit for any 06+ putting down decent power.

I made 367/240 on 91 octane @ 10.5psi with 3.8 pulley with 1200 blower

 

I just ran into this issue earlier today. What I did was trim down the small plastic ridges on the bottom of the pump, and was able to gently force it to clip in place. Been running well so far and car seems to like it more than the Grams 265 I replaced