std rst system is 2 1/4 bore

any s/s sytem is 2 1/2 bore

mongoose u can get 3 inc bore as tube tork as well magnex u cant

I know of 5 rst running well over 250bhp with out any trouble with scorpions on

i have done back to back testing with the zorsts and there is no diff what so ever only with the 3" bore u will see any different

imo magnex fit the best and have a flexi pipe in them, and rest dont come with them which is a shame .magnex as well have the same size bore in the back boxs so do scorpions. it only mongoose are a pain in the ass to fit but are a lot noiser on the motorway as its back box has a bigger bore in it.as with the scorpion u get a nice rore when coming on boost scorpion is not restrictive unit u get to about 270-280 bhp when u look at the likes off sunny tim c&b and TT all got cars over 300bhp proven all got 3" bore zorst a lot of people take the baffles out to make it flow better and make it louder