In a previous thread I was thinking of installing Hunter PGP heads. I have done a little more reading and it looks like the Hunter I-20 heads seem to have all the benifits of the PGP plus it seems like they are a little more rugged, have check valves, and can be turned off individually. I also noticed that the I-20's have a 5 year warranty vs the 2 year warranty with the PGP's. To me this would signify that these guys are a lot more heavy duty and would last longer than the PGP. I am right in assuming this? The difference is only like $3 a head between the I-20 and the PGP's. Not sure if it is worth the extra $$ or not. I noticed that these have the option of stainless steal housings as well. I am curious what you guys think of these as well. Thanks!