Non mandrel bent exhaust?

Ok....For a Naturally Aspirated 318, 2.5" Crush Bent will be overkill.

2.5 Straight Pipe has the flow capability to handle 350hp through (1) Stick of 2.5" Pipe.

x2 would be sufficient for 700hp before it becomes a restriction.

How would I know?

I have stuffed 350hp through a single stalk of 2.5" Pipe...thats how...13.31 @ 106 through (1) 15' stick of 2.5 Aluminized Pipe.

I then upgraded turbochargers and blew 380hp through a single 3" pipe to go 12.77 @ 113 on pump gas.

So, My recommendation for your setup includes Dual 2.5" pipes with a "X" Scavenging Cross Over....It will fit and go over the axles better and fit INSIDE the leaf springs to the bumper if you so desire.

Good Luck.