Im having an sti8 bottom end fitted and are looking to map to 350 while on 5spd gear box, however thats the max for 440 injectors and there are limited and expensive options for side feed, would it be possible to change it to top feed by changing the intake mani etc?

I'd imagine the 440's would be good for 330hp @ standard fuel pressure, pending on supporting mods.

Are they phase 1 or 2 440's?

I run 550 cc nismos ,nissan injectors with a tab filed off the plug and phase adapters.

Or You can get phase 2 440's made bigger by the likes of mark @ lateral performance.

If it's not broke .....upgrade it 😊