I know I'm probably too late to help now but I found using an Allen key to get onto the bolts and then putting a longish tube over the Allen key gave me just enough leverage to crack the bolts. Once they are slightly looser you can get away with just using the Allen key.
Hit it with a hammer.. Doesn't only distress you, but also cracks the crap off the threads, their is another way you can fit the kit if up can't get it off the manifold