Easy, correct me if I am wrong here.. but didn't you have an Akro installed on your 12 for some time before you added the PC111R??
If this is correct, I am not surprised that the addition of a PC improved your bikes performance. Your bike was being fed data for a stock exhaust system, but the MAP for an Akro system is totally different.
As far as adding the PC111R to a totally stock 12, you might be able to tweak out a small increase in performance or driveability. But I would bet that the only way to find this magic spot is by having a Custom MAP built for your bike.
This all brings me to the cost factor... would it be worth $500 or possibly more to purchase the PC111R and the cost of the Custom MAP?? Well I guess that is something each owner must decide on his own...
I personally have both the Akro and the PC111R with a Custom MAP, and I am really glad I replaced the original exhaust system. The increase in power combined with the decrease in weight was definitely worth the cash <img src=http://www.ezboard.com/intl/aenglish/images/emoticons/smile.gif ALT=":)">