I don't know what level your car is power wise but, we (the shop i use here in Denmark) have a customer with an Octavia VRS with a fully built engine and GTX3071R turbo which ran a full Milltek system 2,1 Bar of boost and made 445bhp. When it was changed to a non powervalve system from BCS he makes the same 445bhp but at 1,5 Bar instead
Thats' a whooping 0,6 Bar lower pressure on the system with same bhp
So for lower backpressure and less strain on the whole system, i can only recommend BCS or similar systems regarding back pressure.