funny reading the DIY a decade later. it made a very noticeable difference and ultimately, now that we know what to do and avoid, isn't that much of a hassle. hope it helps!
you didn't mention caring about any other "features" (ABS, cruise control, etc), so your solution is to remove the fuse. voila, no more hill-assist.
now, where do i collect my reward?
don't forget to double check your existing line for a check valve. my 08 wrx already had one determined by the bulge and taper seen in the vacuum line located in the typical sti valve location.
this is a very important post for those affected. thanks power6! i'll make sure to keep my progress up to date but you nailed my status down. waiting on a union fitting and am going to cut the line down a bit and then use a union and two male tube nuts to run new line where the old kinked to make sure i bend it (with tube bender pliers for tight radius turns) to the port safely and without kinks and i should be good.
i'm doing this swap on my 08 wrx which may relate with you newer gens. i have a detailed thread about it here (http://www.3gwrx.com/forum/index.php/topic,20410). someone referred me to this thread and the potential for problems.
i have specific bore diameter information for the different MYs, more photos, and lastly noticed that my car appears to have a check valve already installed in the hose so you may want to double check before shoving on in there.
hope it helps. i'll be sure to post up information in my thread for reference and process for the unfamiliar.
thanks!