So, have me an 2003 350z. The venerable VQ35DE!

Have just installed headers, cat deletes, and exhaust, replaced the intake tube with a better flowing one, replaced the 03 air box with the 06 (to get the velocity stack), plenum spacer and a tune.
Just put down 251 whp on a mainline dyno.
That's peak.
There's definitely been a steady increase in power and torque across the whole range.

That sounds about right, but obviously unremarkable.
Should I be underwhelmed or happy enough with this figure.

 

I'd say it's a little low but dyno plays a part, as well as location and header choice, a lot of them lose power.

 

I’d say that’s about right ...

back in the day I did 246hp with some bolt-ons

but as Dark said, many variables to consider...

 

All dyno's are different so you can't really compare dyno results. The only thing that matter is if there is a difference in HP before you put all those parts on? So did you do a dyno run with your complete stock car?