Im trying to get all the parts together for a diy thru hull exhaust. I pretty much just want it going straight out the back. I have a 87 omc 5.7(gm350). I got a pair of 4" exhaust tips. over all length of tips are 10". 4" inside the flange and 6" outside the flange. I know my risers are 3 1/2" so i need a reducer/adapter. My question is what is the degree of the risers? I was thinking 40-45 degrees.
