It doesn't matter what bhp you want, just get a ecu, and if not mapping yourself a tuner/mapper you are happy with and have confidence in.
I use a K3, they've been K6 for a while now to excellent effect, mapped by DW from emerald, seriously have NO complaints, I took up about 1 hour of his/rollers time yesterday, but had a "issue" with a monumental air leak, so took car home to fix, he didn't even charge me, found fault and fixed, with bore scope, needed a running in map for new engine.
So long as the ecu can do the job function wise, and it's mapped correctly/well then make in not important, I personally think it's 10% ecu 90% mapper that makes the difference, and that's why I use emerald.
Emerald will NOT send out a ecu without a base map, this will be the nearest map they have for your engine configuration, to clear any confusion.
tabetha