Most hp on return less system

Nissan370

Ok so what I'm hearing is I may be good for high 500
With my current fuel setup
But for 600+ go return
E85 is just to far from me to be reasonable
And I think I can manage the water meth levels
and have them tune the car without going nuts on the timing

So returnless..340lph and 750 cc should be ok

If nothing else that water meth is used for a bit more safety
I don't drive my car like a mad man but I am all for reliability

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370z vsr motorsports single turbo/built motor 9.1cr 525rwhp/450rwtq @ 10.5psi (stock maf maxed out)