You need to make it in sections , ie. the dump including wastegate bleed type pipe ( ala HKS dumps ) and then the front pipes.
Make it as one unit and you will never get them on.
Butler exhaust did a set for S dickson ( grey GTR up your way ) and SWORE he would never do another set.
Jeff Garland at Exhaust Dynamics could be worth a shot but at the end of the day , it is a lot of money for a relative small gain.
Would expect dumps and front pipe will be around $ 1500 for a good stainless setup and you will gain maybe 15KW.
Apexi power fc is about $1700 and have been told is good for 30KW.Also it 5 min job plus tuning
Cheers
Ken