Recently installed a pair of the APR diverter valves as a follow-up to my prior secondary cat bypass pipe install. I don't have any dyno measurements to offer, but I will state that the reliable seat-of-the-pants driving impression is that even just these two simple upgrades have made a noticeable improvement in the responsiveness and driveabiity of the CTTS.

Next decision point is to go for the IPD plenum or straight to the ECU tune. I'm leaning towards the plenum, then followed up by the tune after which I'll call it a day, but other than IPD's website claim of HP gains, there doesn't seem to be anyone who's done a before and after dyno comparsion of just the plenum.

 

Sounds like the same mods Ive gone with, and ive done a tune that I'm happy with. As far as the IPD Plenum its been discussed on here before actually recently. I think personally Im not going to run the IPD plenum I have my own thoughts on this not sure if Its worth it compared to the stock.

Sounds like your in the right direction man good for you!