It’s like this...
Breathe through a 4 inch PVC PIPE.
Any restriction?
Breathe through 6 inch PVC PIPE.
Any restriction!
In both cases it will feel exactly like you are breathing in an open room.
Theoretically. 6 inch PVC pipe is less restrictive than a 4 inch PVC pipe. So why then does it not make a difference to suck in a breath through either one?
Because the flow and negative inspiratory force that a person can generate is far less than the nominal amount of restriction offered in a 4 or 6 inch sized pipe.
In other words.... if the engine is breathing less than the flow restriction that is present.... making that flow restriction less isn’t going to do very much.
I’m sorry I don’t have the dyno graph(s) any more but I did have one of a kooks on a raptor with a stock catback, stock tune.
The horsepower curve could have been almost superimposed... maybe 5-7 horsepower at certain points.
Maybe with a catback... a tune... etc.... maybe it would be additive and you’d see a little better response because the engine would be breathing more.... but I’m not so sure.
If you look... switzer put down 550 with their big turbos and stock downpipes and stock exhaust. They’re just now looking at opening things up.
I think ford did a decent job with the outflow this time.
