breesej, your math is correct. There weren't any miscalculations on my part, I'll explain why I chose the 2.5". If you read some of my earlier posts in this topic, I was going to use Racing Beat's dual 2" to 4" megaphone and no muffler. I decided not to use that because I have to drive this to events in other cities. I don't have a trailer -- I would like one -- so not driving it around town is not an option. I wondered if I could use a megaphone and muffler and see what I could fab. I ended up in the position where I could afford a muffler and a nice collector or go with only a megaphone. I really didn't see the extra money on just the merge pipe being a huge benefit. Put that money into maybe a crank pulley instead. Maybe next season though!

Now I have only two weekends left if I want to port the TB and manifolds before the season starts.

BTW, I just took off the old exhaust system last week. Man is that fucker loud when there is only ~8" of pipe from the exhaust manifold pointing towards the ground.
*ears bleeeding*
Shoulda pushed it out of the garage first. *shrug*

I like the sound of open headers with the Racing Beat Uncollected Road Race headers. Too bad it's loud as fuck. I am almost done with my exhaust system, I just got to get it coated with a ceramic now.

I just found this thread... I work at MBRP performance exhaust. I know it has been years since this thread was active but I just wanted to say hello on behalf of the company. Let me know if anyone in Ontario is in the market for a custom mandrel bent stainless steel turbo back exhaust! I'd be happy to help put something together.