3" catback

You'd probably lose too much back pressure. Go with 2-1/2" with 3" tips.

 

yep, unless you have a mega hp/airflow engine there is NO NEED for a 3 inch exhaust.

 

yup...you'll probably loose some low end hp/tq. Unless you're running a s/c (or at least really high-flowing heads and radical cams), there's really no need for them on a 4.6.

 

'for high horsepower applications'.
if you plan on upgrading to the 400hp range, then sure,
however,
as previously stated, youre gonna loose some power until you
start making some pretty high hp numbers