No, you can install the exhaust all by itself. The bike may not run as "good" with the correct ecu, but it will certainly run.
A ton of people on here are running different exhaust setups without the dp ecu(myself included).
I would send you stock ecu to be flashed/mapped for your exhaust, but it is not needed to ride the bike.
so how can i get the best performance with the Termi exhaust?
Are you meaning that even i change the ECU to 796 Termi ECU, the bike maybe not run as "good" ??