Just for fun, I quickly replicated a ~300HP Muliport injection V6 engine based on info from Wikipedia. Here is kind of what I see...
Using these specs from Wikipedia:
Bore x Stroke: 3.760" x 3.205" = 3498cc
Compression: 10.6
Fancy Nissan VVT techs
All Aluminum Block & Heads, Forged Steel internals, DOHC
Redline: 7500RPM
Twin Throttle body intake, dual exaust
I matched as close as possible. Ended up with a Cam profile of 38 & 61, quality +7 (to acocunt for their fancy VVT techs)
Runs on regular unleaded. Currently using a Fuel Mix of 13.0, Ignition Timing at 50, +2 Quality fuel system
Tubular Headers, Dual Exaust, 1.75" Diameter, High flow Cat, Two Reverse Flow Mufflers, +4 Quality
Here's what I get
Top end power is a little too high, but getting right around 300HP at 6800RPM, 258lb-ft @ 4700RPM.
Detune the cams, retart Ignition Timing, lower exhaust quality, and leaner fuel mixture, and you can replicate most tunes that Nissan uses pretty closely.
I'd say the hardest thing to replicate is the exact low end torque, IMHO.
Hope this helps!