Ok I'm in the process of a 4.3 swap from the under powered 2.5. I've got the ax15 behind the 4.3. I keep seeing everyone doing these engine swaps but I'm not seeing anything on how the exhaust is being run. With the 2.5 it runs under the oil pan. With the 4.3 the manifold runs to the back of the motor. So the question is how did you run your exhaust? Daul or single and what size would be the best diameter the the 4.3?