as kaytrim stated. Either go with the ultimarc ipac 4 or 2 keywiz or gpwiz. On the keywiz/gpwiz, make surethe2nd one is a different id.
If you want to save a few bucks, look into the eco series at ggg.
I currently have 2 gpwiz eco in my 4 player cab and so far experence no delay or whatsoever. The eco uses ide cables for wiring.
Both product are highly record.