I run a Jp-1 pipe with the short OS header on my Vspec in my Jammin CRT Pro. It is the same as what Chad Bradley uses. I have great bottom and top end. The trick is not to use the long Jp-1 header. The Jp-1 still gives the engine great torque and the short header really allows the top end to come alive.
On my Jammin buggy I run the OS 2050 setup with the Vspec. It gives a bit better milage than the the JP-1 does.
If you run on a real short, tight track you could try the long JP-1 header if top speed does not matter....but I have not yet run on a track to try this out.
Both of these setups are great but remember that your clutch has to be set properly to get the response from the pipe and header.
In the truggy I use the Jammin silver shoes with the gold springs and in the buggy the silver shoes with the black springs, both with stock gearing.