hi everybody.
Has anyone ever tried to do head work for tuning on the H3?
From my views the intake looks great but the outtake is very small and like a bottle neck.

Has anyone tried to enlarge the exhaust side to what the gasket size is and also a portion in the exhaust header?

Or anything else recommended?

 

You talking I5s? There are several headers on the market, some members have tried them.

Head work on a 5000# + off road vehicle powered by an I5 would be a very low $$ to power return. Stick with the known mods, tune the PCM, buy and Intake and filter, Cat back exhaust. port & polish the TB and enjoy.