The raven system is just a basic copy of the Christen system only a lot cheaper! The T fitting really has nothing to do with it being made by Raven or Christen, but rather the use of the vac pump pad fitting that can and has been used for years with the Christen systems as well. See p/n 07-06790 from ACS or
http://www.aircraftspruce.com/catalo...2pumpadapt.php You can install that adapter with either system.
Anyway, they are basically the same system. I happen to have the Christen system on my RV6, because I don't recall the other one being readily available back when I built my plane. That being said, if I were to do it again today (and I probably wouldn't) I'd just buy the cheaper one.....
Just my 2 cents as usual!
Cheers,
Stein.
RV6 - AEIO-360, Minneapolis