The injectors will work fine as long as the MAF or chip is tuned for them. It's doubtful you'd see a gain or loss either way, it's just a matter of tuning for optimal performance with what you've got. If you aren't planning on tuning with a chip, then stick with the 24's. If you are, then it's an easy change over.
As far as the exhaust, I'd go with Keith's recommendations as I beleive he used to do something with flow dynamics for one of the big three.
Rick
