If you don't want to lose the exup then you will have to fit an original system, If your exup is no good and you are not worried about it there is a pattern down pipes for the thou, there is one for sale In the sale section, that system is a 4-2-1 rather than the 4-1 as original, that pipe will give an improvement in the midrange so should help to replace some of the power lost because of the lack of an exup valve.