I ran with a standard WRX TMIC with the VF34 at 340/400 for long enough but was advised by AndyF to upgrade to the STi topmount. He informed me that the STi TMICs were becoming more and more difficult to get a hold of because people were realising just how good they are and where holding onto them. Anyhoo, once I got a hold of one and got it fitted (with a bit of jiggery pokery at Hypertech) I revisited Andy and he checked the map. After another going over, the car put out an extra 1bhp, ha! Then again, I still have the standard WRX undertray. Bear in mind though, ICs are support mods, not performance mods; so you wouldn't see an increase by adding a bigger one, but the greater safety margins offered by a larger one will allow the mapper to give you more power as the bigger IC will keep things that little bit safer. (I think!)
The injectors on the 06 Hawkeye car were all I needed, so need to uprate just yet. As for the injectors in the Blobeye... no idea!
Anyhoo, hope this helps
Edit: Just to say that after one session at KH with the power upgrades, I destroyed a set of standard discs (warped and heat fractured) and heat-damaged the pads. If you're going to unleash your new power, you really are going to need bigger stoppers!