You may have added a few low end lbs ft with those mods. Not surprised at your flash stall with some bite and the 2.45's. That's probably as good as it gets considering anything with a upgraded cam will hurt torque in the just off idle range.
As far as the OP's question, a few hundred one way or the other isn't going to make a lot of difference with a stock unit. If your looking for more performance with a stock engine, i'd look elsewhere for a upgrade. As much as the cheaper units are shunned upon, even a mild B&M or TCI type converter would probably give you some more juice with a stock setup.
