Ok i'll explain.

The throttle body that the manifold is designed to be used with looks like one of those 70mm items from the states/ebay.

Now we all know that a cossie (similar capacity engine) will easily make 450+ bhp on a 55mm throttle body and that for the engine to make that much power there is easily enough cylinder filling to det and destroy the engine if the AFR is wrong.


To achieve the the same throttle plate area as a 55mm body with a 70mm body you only need to open it 61 percent (roughly 55 degrees rather than 90deg at full)

So what i'm saying is that you could be driving along at 61 percent throttle making a lot of horsepower. Now look at the angle the throttle plate would be at!!

All the air will be diverted into the the first two cylinders. There will be a huge disparity of air flow between cylinders with the closest cylinders running far leaner than the rear two. You would not see this on your AFR readings. Only an average of all the readings. The first two cylinders could be happily detting away and the first you would know of it is when the engine fails.

The manifold might have been tested on a flow bench but i can gaurentee they didnt bother mounting the throttle during the tests or they would have never mounted it as they did!