I found this link from barotary: http://www.atpturbo.com/root/releases/release091004.htm

...would a turbo RX-8 benefit from this mod? Discuss.

Pics below:

 

There's nothing wrong with a butterfly valve in the system. Quick Time Performance has had one for quite some time now.

The problem with THIS one is it's orientation. I don't know who they are trying to fool complaining about stock restrictive components. The way they have this thing oriented there isn't going to be much going out that thing but noise. A dead 90 degree angle is absolutely terrible for flow and probably more destructive to power than the stock exhaust components. What Quick Time Performance (QTP) does is to use a Y pipe rather than a T so that the air can get out much easier. This does work.

This is definitely a waste of time for a naturally aspirated RX-8. For turbo use the idea is good but the flow pattern still isn't. You may also potentially run into another problem in that the engine is tuned around the turbo being installed on a stock engine with a stock of similar type of exhaust. For every psi of exhaust backpressure you free up, you've essentially added 2 psi of boost. You aren't tuned for that. This mod runs the risk of really hurting something unless the ecu can compensate.

Keep it simple. Ignore gadgets like this. If you want a turbo, fab up a new high flow exhaust. Nowhere does it say that you have to have a loud exhaust to have a good flowing exhaust. You can have fairly quiet when you need it and fast when you want it in the same system without resorting to these types of products.