I was just told by my friend who was talking to a local rotary mechanic that unless I upgrade the secondary injectors I won't see any gains from an aftermarket exhaust. Can anyone shed some light on this for me?

 

Not really. If its an N/A, an open exhaust is just fine without extra fuel. May have problems with aux intake port actuation.

If its a turbo, with a full 3" exhaust, then bigger secondaries would be good insurance. But it would be running rich without a S-AFC or something to control it. Basically, you can open up the exhaust without bad side effects. Its the best way to get power from a rotary.