Neo187H

How is it that people are still debating over this exhaust thing? Its been proven on Shumby's car that the extra flow from the exhaust causes a loss of boost and thereby power. This is due to the overlap of the valves letting the intake charge flow right out of the cylinder and into the exhaust before it can ever make power.

The issue is valve overlap, the band-aid solution is to increase exhaust backpressure to stop the intake charge from flowing right out of the cylinder. NA engines want more valve overlap than FI applications to increase exhaust scavenging and such while FI applications dont want it because this kind of thing happens.

So until someone cracks the VVEL control module and allows tuners to change valve timing we will be stuck with this issue, increase the boost to make up for boost "lost" or increase exhaust backpressure.

Edit: I should add in that this is what I suspect to be the issue based on my knowledge, I can't say this is for sure whats wrong with it as I don't exactly have the means to back up that statement.