There seem to be a number of different chips available to increase horse power and torque. Has anyone had any experience that was positive, what brand and model?

When Nissan redesigned the 4.5 [90-95 Q] they rung a good bit of safety and over design from it............increasing HP from 278 to 340 and torque from 292 to 333.............this 14>22% bump up left maybe 5% safety factor.

Compare all the other manufacturers 4.4, 4.5, and 4.6 engines to gleen what is possible...............not much!

Using ethanolized fuel will result in a 2.5-15% decline [from published spec] in peak torque output due to a lower BTU content in mixed fuel.

Finding oem spec fuel [as used in Japan to test engine] is almost impossible in US currently as we stretch more gallons per barrel of crude.

Try 100-114 no lead octane racing fuel to see what the true potential is.

Before you go spending on chips.