I have a EVO with RMR intake and a gutted-out stck EVO cat. I'm planning to replace the gutted cat for the ultimate racing 3" test pipe and adding a RMR 3" downpipe and 3" cat-back. Do i need to get some kind of fuel controller to gain the optimal performance out of my EVO or will another reflash by Al be good enough. I've heard of people tuning their stock EVO with the Apex S-AFC Spec II and gaining like 15 whp. I already had a reflash done for the intake and cat, but the car seems slower then before.

I'm also going to add a Greddy Profec B Spec I within a month.

 

yes, you will need another tune or an afc tuned...to gain more power off your modes