You'll be lucky to get anywhere near Dean before christmas. Possibly after. And he's nearly a 6 hour drive from tidgey haha. Your options are either off the shelf or custom. Both have their benefits.
It won't be cheap. Be easier to buy a rerouted screamer pipe and decat from WEPR outright. Rather than sending yours over to be modified. At least then you can switch between setups.
Sacha might be able to supply a new screamer and decat. Either that or get somewhere local to fabricate something. Frankly its more hassle than its worth. My advice is man up and live with it lol.
You will lose power by rerouting it back into the exhaust. You'd need a custom screamer pipe to go from the wastegate, then either welding or flanging onto the downpipe.