HP Gains Stock vs. Catted X or Offload 2.8" Pullied Cobra

[351stang]

The car put down decent numbers with the stock factory H pipe and magnaflow catback, so I'm wondering what people estimate that a catted x-pipe or offroad x-pipe would gain.

Would I need to retune?

Dyno for reference (mods in sig):

 

[351stang]

I should have searched FIRST. I found a bunch of old threads going back to 03 that indicate 4-10 HP. Sorry for cluttering up the thread.

Mod's can delete and won't hurt my feelings.

 

[P49Y-CY]

Not much of a gain in horsepower, but a tremendous change in exhaust sound.

 

[AznPrswayzn]

^ this. I have an catless x-pipe with magnaflows and it really wakes up the exhaust note