The A-trim can and will get you to 400+rwhp with your set-up. Keep the stock pulley, add a larger crank pulley, powerpiep, good tune, and you're there. However, I would also agree with the others and go with the S-trim if money is not a deciding factor. The S-trim will give you room to grow in the future because believe me, you will want more boost and power down the road. I'm a Powerdyne owner that not only is stuck with no room to grow, my blower doesn't have the reliability of a Vortech.
Then again, isn't Vortech replacing the A-trim with the SC-trim. It's an S-trim with the tips of the vanes cut off to limit the boost but make the A-trim blower more effiecient. Price is supposed to go up only about $100. Might be a good way to go. Good Luck
