hmm, it cut off the end of my reply.
Having HK makes adding or upgrading harder, in the e36 as well. If you want factory premuim and dont want to change it, then HK is good. If you have the slightest inclination to get someinth aftermarket, go with the regualr system.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>