I just ordered a 50 series delta flow, I'll let you all know what it sounds like when I finally get the time/finances available to do my exhaust.
Don't forget that a 2.3 is a fairly big bore 4 cylinder, therefore, it wont sound ricey. The formula for displacement I believe is the following (someone please correct me if I am wrong):
displacement = bore x stroke x # of cylinders.
The 2.3 is 140ci, whereas they 4.6 is 281ci. So, thought of logically the bore and stroke should be the exact same as that motor. Exactly half as much displacement and exactly half as many cylinders. Anyhow, my point is that a flowmaster should sound alright on a 2.3 considering it has got a fair amount of volume per cylinder.