3" exhaust is a possibility when the current one needs replacing but increasing the boost concerns me a bit in terms of reliability & longevity. This may well be a result of my ignorance about such things, but it is reassuring that in stock form I can take the car to any Nissan workshop & be reasonably confident that they know what they are doing. Start changing the basic parameters & this may no longer be the case. Not saying you're wrong, rather I'm inviting you to convince me as better fuel consumption/greater range is attractive.

Cuppa