My is a 2015 F3-S SE6. I am trying to figure out my best options for exhaust to utilize the Monster ECU re-flash.

I currently am running a HMF Racing exhaust. This exhaust deletes the cat. I do have a BCT baffle installed to help with back pressure.
https://www.hmfracing.com/exhausts/can-am/spyder-f3-s

I was considering putting the cat back on and installing either the Akrapovic Sinister Silencer or the Akrapovic Straight Shot Silencer. Does anyone here have either of these exhaust and would also be able to tell me the difference between the two? Also, would I need to buy the heat shield replacement kit right away, or is that simply a "maintenance" item that comes later?

The only other "performance" mod I have is a K&N air filter installed.

Thanks in advance for the help and opinions!