Hi! need some advice on my 07 SD. The beast is currently running akrapovic cans. I'm about to put a new filter in (BMC air filter). Question is if the SD starts breathing better because of running a decent filter do i need to Rejet / Remap the bike?????? If i don't rejet etc.... will it cause any damage to the motor???? help!!!

Put a pot of tea or coffee on (as per preference), pour a big mug of the stuff and read the tuneecu tread dude.
Not to be rude but this has all been answered before so have a read and let us know if you have any more questions.
To get your started your bike could have the original map in it or the akra map (put in by the dealer if you buy the akrapovic pipe from him).
If it has the akra map it is not going to run lean at all, the map is rich as a Saudi sheik in a full cream bath.

BTW we don't talk rejet here...

Yes, it's advisable to remap the SD after cans and filter.

Do you have the Akrapovic map for the exhaust? If so it's ok for the air filter too

It's all around the forum with many threads about akrapovic map ( can be download by you with the tune ecu cable and free program or at the stealer for a fee usually ).

With the tuneecu you can remap it with injection, ignition, dual cylinder etc etc

Rejet on the lc8 is for the 950 adventures and supermoto only. All Superduke came with the 990 injection engine