It sounds like the OP doesn't understand it's the dish electronics (ie: LNB &/or switch) that max out on # of tuners, & NOT the splitter itself.
If they currently have a SWM LNB, the max # of tuners you can have on that dish is 8 - regardless of how "big" the splitter is. Do you know for a fact which kind of LNB is on their dish now?
Then, you need to find out how many tuners (ie: model of receivers) they currently have. HR34's have 5 tuners, HR2x DVR's always have 2 tuners, & all other receivers are 1 tuner.
Bottom line, if what the client wants to add on, exceeds 8 tuners, you're going to need a setup as described in the previous post.
Keep in mind though, it maxes out at 16 SWM tuners. Also, for him to buy the equipment above (ie: new SWM switch & legacy LNB) is going to be very costly, (at least around $200+) & THAT'S not even including the added receivers.
You probably would be better off having him call D* & get a deal from them. DirecTV will supply all the required pieces needed when you have them install new receiver(s). Most likely, they'll do it for way cheaper (sometimes FREE) than you can even buy all the parts for.
And BTW, even if he has YOU do this, D* WILL put him on another 2-year contract for activating ANY new receivers - so another reason to let D* handle this to begin with.