what is the car used for ?
if its atrack day car best route would be to remove ur cats and possibly a side exit exhaust no back box resulting in no back pressure
aiding quicker release of exhaust gasses
if the car is used on road replace your existing cats with a high flow sports cat and and put on that h&s back box to retain /amplify the all important flat 4 burble it's a good compromise for a road /track application (key thing make sure the system is running 3inch mandrel bends throughout to eliminate back pressure and to aid accurate exhaust flow ) I hope this has been helpful
best car show ive attended ,i went 3 years ago loads of owners clubs parts promotion ,drift shows circuit work im definitely going
with my family great day out would recommend it
it would be brilliant if soc had a club stand there