what is the best turbo with a T4 flange?
 

I like low end HP and don't care much about high end HP.

I'd like it to spool fast with HP ranging from 300-350

I don't know what size injectors to get. Any recommendations (primaries and secondaries)?

This is what I have:
S5 TII engine and transmission
Microtech LT10
HKS manifold
HKS standard wastegate
HKS style intake
Greddy Type RS BOV
Greddy FMIC
Walbro 255
Corksport Power Series exhaust
Pre-mix

I have this turbo in mind:

HKS Universal
T04S, .84 A/R, 60T, T04 Flange, Ext. WG, 550PS Output, 17813

It is a bit pricey, but I want quality parts that won't damage my engine. Are there any other turbos that are comparable?

Thanks in advance

Go smaller; Garrett T04E 57trim P trim .84
Even a Smaller to4B would work fine; B25 for example

Yeah, from what it looks like, that one has a 550 PS output, which is much more than you're looking for.

where are several places online that I can get the Garrett T04E 57trim P trim .84

I have this turbo on my s4 sp turboII. It's a great street/drift turbo, with the .84 exhaust side. If you get one I'm pretty sure you will enjoy it too :)

good luck.