VXOC Astra-J/GTC

as above...has anyone actually had a car on the rolling road to see if there is any benefit to having a Flowmaster? and to see if the standard air box is better with a K&N panel filter??

they are very pricey some people like them
and some see no difference or the point as a panel filter is more or less the same thing
but they say they sound good
a few with the vxr j have tried them
best Google about and see what people say about them a few on the corsa sites have also have them.