Ok, I'm about to re-do the exhaust from the header back with 3" tubing and wanted to ask you guys one thing - are you coming right off the collector with the larger diameter tubing, or are you gradually stepping up to it? The reason I ask is that I read an article on S&S's webiste that says in part
the collector outlet diameter only needs to be 20% larger than the primary tube diameter. (Example: 1 3/4" primary tubes need a 2" collector outlet diameter.) The rule of thumb here is two tube sizes. This keeps the velocity fast to increase scavenging, especially at lower R.P.M.s. Going to a larger outlet diameter will hurt the midrange and low R.P.M. torque. The amount of straight in the collector extension can move the engines torque up or down in the R.P.M. range. Longer extension length will pull the torque down into the midrange.
this makes me wonder if maybe I should be running a short section of 2"-2-1/4" tubing off the collector and then stepping up to 3". But then again, this may be more geared toward street applications, and may be all wrong for our motors. So, I thought I would ask you guys what you're doing, and how well you think it works.

Thanks.