Exhaust Bottleneck

[Neejay]

I bought a Buddy Club Spec 2, but in all the years of hearing opinions on them, I've never read or heard that it had a 2.5" resonated section.

At the flange, it's 3" then goes to a 2.5" resonated section then back to 3" piping.

RB25: 10psi, 3" turbo outlet, 3" downpipe, 3" test pipe, to this exhaust. Realistically, how restrictive is this 2.5" bottleneck?

[codyace]

While it certainly it presents a bottle neck, it's not going to ultimatly effect 'to much' power for a lower boost/power car. Once you want to crank the power, I'd suggest going a full 3"

[Neejay]

While it certainly it presents a bottle neck, it's not going to ultimatly effect 'to much' power for a lower boost/power car. Once you want to crank the power, I'd suggest going a full 3"
Ugh...I don't want to have to purchase another exhaust down the line. wtf man. I don't really plan on going too much over 300hp to the wheels. I'm already at 277hp/277tq.

Someone explained it to be like this: YouTube - The Differential Pressure Flow Measuring Principle (Orifice-Nozzle-Venturi) (http://www.youtube.com/watch?v=oUd4WxjoHKY)

It's a venturi effect-the same principle of the carburetor and Nissan's SCV system. It's resistance that increases velocity also. You have to imagine air flow as if it were water. Imagine putting your thumb over a garden hose outlet, decreasing the diameter of pipe but still allowing flow.