No you don't need to remove the end cap. Here is a copy of the maintenance instructions.
S I L E N C E R I N S T R U C T I O N S
Thank you for purchasing the FMF Turbinecore 2 silencer for your motorcycle.
Your FMF Turbinecore 2 silencer has been developed using the latest design, testing and
manufacturing technologies. Your silencer is manufactured from an extruded aluminum canister, with a
stainless steel stinger, performance flow endcap and uses space age sound-absorbing packing material.
The FMF Powercore 2 is designed to give you a balanced power enhancement in a lightweight, fully
rebuildable, factory sounding silencer.
To repack the silencer remove the 3 screws from the front of the silencer using a 4mm allen wrench. Do not remove the
rear endcap. Hold the stinger in one hand with it pointing down, and gently tap the aluminum bracket on a wood block in
a downward motion to slip out the inner core assembly from the canister. Be careful not to damage the silencer. Unwrap
the packing from the core and discard. Using a wire brush, clean the perforated core and do a final wipe down with
contact cleaner. Wrap the core with new FMF 2-stroke packing and secure with a strip of masking tape. Do not pack too
tightly, as this will hamper performance. Before re-installing inner core assembly, apply a thin layer of hi-temp silicon on
the front end cap, where the aluminum canister slips over. Slip inner core assembly into canister making sure that it fully
seats in the rear endcap. Re-install the allen screws until snug or tighten 1/4 turn after the screw makes contact with the
canister.