Has anyone tried the Magnaflow 4" exhaust on their rig yet. I e-mailed them and they said it's a 3. 5" down pipe, 4" the rest of the way to a 5" tip. He said the reason for the 3. 5" down pipe was so the turbo has time to spool up????????? WTF! Anyhow, does anyone know how good the quality is on this system? Thanks for any input.