The s-trim comes with the better discharge tube, by-pass, and msd btm. It also has better bearings. I'd hold out for the s-trim.
If you add all the upgrades to the a-trim it will cost you more than the s-trim package and the s-trim bearings are better.
I have an a-trim and know first hand. As a matter of fact.. I really don't have the money to buy an s-trim right now but I just might be willing to give you a deal on this a-trim and bump up the ccard a bit.
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Rick
My 89lx(updated 11/5/2000)
My 97 Cobra