Y pipe should be fine as an after market y pipe back system fits to the OEM y pipe, so in theory a OEM y pipe back system should fit to an after market y pipe. Also what you can see in the y pipe are flexi joints and not silencers/resonators.
Are you thinking of getting a second hand OEM system ? As new will cost a fortune ! Why not get a new stainless system ?
It’s odd that your scorpion exhaust is too loud as it’s one of the quietest exhaust available for the zed. Like others have said it’s more likely that you have some sort of decats or maybe the baffles in the back box have gone.
As for the exhaust itself the scorpion has no resonator in the mid section,(which has a sleeved joint to the back box) nor will an OEM back box fit to it.
Your right, my genuine DE ones cost me £80 from the states ! I do have a bad case of zeditus though and like how they have the three dimples in them to match the door handles etc. !
Both MPSS and MPS4S available on Tyreleader
https://www.tyreleader.co.uk/car-tyres/michelin/pilot-super-sport/275-35-zr19-100y-439038
https://www.tyreleader.co.uk/car-tyres/michelin/pilot-sport-4s/275-35-zr19-100y-804962
Get yourself a ctek maintenance charger and leave it on the battery until March
here’s the one I use over the winter.
https://www.ctek.com/products/vehicle/mxs-5-0
I can’t believe there’s still original exhausts out there, mine failed years ago ! and I’m now on my second aftermarket one. The first being a Japspeed, better know as crapspeed and now I’ve got a invidia Gemini which I can highly recommend.