I am installing straight pipes with these resonators on my 4.6is this saturday. (in place of the stock resonator naturally) Would be curious of the sound difference if I installed an x-pipe behind them as I will still have room...
http://www.verociousmotorsports.com/...sonator-12-OAL
But I do hope to have room to properly install some cutouts with QTP actuators on them in the near future for that extra growl at the flip of a switch when I want it.