exhaust question

[raptor84]

Im building an offroad truck for the TORC Series. I have to reduce the exhaust from 3 inch to 1 1/2 for 24 inches.. I have heard of reducing it right after the manifolds and that will help with torque? Can anyone tell me where the best place to do so is?

[oldandtired]

You remember the old trick for determining collector length?
Spray some paint on the collector and where it quits burning the paint off, cut it there. This might work as an indicator of where to neck down you tubing.
Just a speculation. Dave

[raptor84]

never thought of that.. i have a guy doing the exhaust for me but trying to help him and me get the most low to midrange power out of the truck
thanks