[Sean Roe]

Originally Posted by radta7

what's a typical increase on a 97 with headers, exhaust, rt cats, smooth tubes and filters?

I'm not sure what octane of gasoline you're using, but it can vary.
Basically, the HP gains come from two factors.
#1. Making the air / fuel ratio flat and ideal.
#2. Optimizing ignition timing for the gasoline you're using.
The farther the A/F and timing are from ideal, the larger the gains. If you've done a lot to increase air flow and are on 91 octane fuel, the gain will be smaller as you can't run as much ignition advance and the increase in air flow automatically improves the otherwise excessively rich AF ratio above 4,000 RPM.

Here's a typical stock Gen3 using 93 octane. Only mods before flashing were Mopar cat-back and high flow S&B air filters. This is about what one would typically expect on either Gen2 or 3. Sometimes more is gained at lower RPM when the engine is running too lean there. A larger torque gain can result from adding the fuel needed.