I have everything the TR340 package has on an O3.

1. What kind of power increases could you get with these mods?

2. Would it be better to get the O2 Housing and 10.5 hotside?

 

The fuel pump and injectors probably won't add anything unless you're setup is lacking fuel delivery (something that isn't an issue with the TR-340). A dyno tune may get you some bigger numbers, but won't necessarily correlate to how it performs on the street/track. The O2 housing and 10.5 hotside should provide a good bump in power (most notably in the upper RPMs).