Go port before upgrading the lpfp. My understanding is that the upgraded pump is mainly needed to supplement E50+ fueling as E requires more fuel to be pushed. With meth you should be able to push 600bhp with your current setup, assuming your turbo isnt restrictive. I have no knowledge of the...
Eu car running the setup you are asking for:
Downpipe & full exhaust
Chargepipe
Pure800
Visconti flexifuel kit
Makes 550bhp on E45 mix.
I would reach 600 with both E45 and Meth, but I will probably look into port injection prior to meth due to the long term advantages of a dual injection...