I just changed to a APEXi N1 muffler. What should I tune ? Do I have to redo both the Fuel Map and Timing map ?

 

Read the "how to tune an evo" sticky. There probably wont be much change, unless you're on a stock tune now. And there is a good chance you are hitting higher load cells that may or may not be tuned. The best suggestion is to log and tune accordingly. If you post up logs, you'll most likely get some help.

GL

 

Thanks.... I just want to make sure I'm not missing anything.

I pump up the lower rpm timing to compensate for the slightly poorer moving off w/o boost. That's abt it. The rest feel good.

Yes, it's hitting higher load faster and further.