Ways to increase HP

[Type 100]

Lessening restrictions in the intake-exhaust path could also tap some few sleeping horses.

(ie IHE mods, cylinder porting/polishing)

Two cents...

The problem here is with newer cars such as the GE Jazz, GM City and FD1 Civic 1.8. One trait common to all those cars is that the header is no longer replaceable/upgradable. Basically, the header is molded as part of the engine block.

The "header upgrade" for these cars is essentially just a delete of the catalytic converter and a swap to a less-restrictive downpipe.

With engine-building techniques like these, Honda and some other engine builders seem to be bent on releasing as much power in stock condition from their engines...or making it more complicated/impossible to modify them, depending on how you look at it.

FYI