ok this is my opinion about the pipe, it shouldn't matter how the track is, if an engine will perform better with one pipe than with the other regardless if it gives it more bottom or top end, then use that pipe, the 5 port has a lot of torque, and don't need anymore so I don't think the DYN 007 will help, you probably will be spinning tires and have no traction, just googled the STS 0403 pipe and according to people it is a Mid to Top pipe which will probably suit the 5 port better, but then again, I suggest you try both pipes and see which one you like better (performance, fuel mileage, etc)

I also have the 5 port, I have tried the JP-4, JP-3, Hyper 2059 and an OPS Pipe, I'm relly impressed with the performance of the OPS pipe, it kind of smoothed out the engine and it gave great top end, my 5 port has never been so smooth with this pipe, I really recommend it.

I couldn't find the OPS anywhere else but on ebay, it's like this one: http://cgi.ebay.com/OPS-ALUMINUM-PIP...QQcmdZViewItem