Hi all , i have a s1 and i recently put a janspeed on it as i wasnt happy with the standard exhaust,i have a cat on it which is empty as on my last s1 exige i had- when i did this it caused the popping and banging on overrun. however this doesnt do this on my current s1 can anyone explain why or how i would get that back. a few on the forums have advised lots of different things such as take the packing out of the silencer or change the ecu so that it overfuels which i dont want to do to protect the engine. there is unburnt fuel getting through tho the cat as for example if im in 4th and change to 2nd there is a very faint popping going on but no where near as loud and noisy as my old one did.i dont want to damage anything as when i bought the old s1 it sounded like that without having to change anyhthing and obvioulsy dont want to affect the engine on this new one.how could you fuel on overrun or keep it open if you like any advice appreciated regards