Joshuaua, you need to study up more on anabolics.
John89231, it's very possible that you would retain more water on 500mg vs 350mg because you could be producing more estrogen=water.
That said I can't say how big a difference it is.
I don't see anything wrong lowering your test dose, but you say you aren't noticing any bloat so it kinda makes me think that maybe you don't need to lower the dose.
It would be good to know which ai you are using and what your bodyfat % is.
Carb depleting/loading and sodium depleting could help right before the shoot and possible increasing the ai dose "might" dry you out some more, but you don't want to eradicate every last bit of estrogen or you'll feel like shit.
Anavar, winstrol, masteron etc can all help you look harder and I hear winstrol can have a very noticeable drying effect if your bodyfat is low.
I know Dave Draper admitted to using winstrol only and for me it's obvious as hell looking at his old pictures when he was or wasn't using it.
I'm sure there are more than a few pro's on the board that can elaborate better than I can.