What can I say, you and Dash makes a good team and your work is improving very fast.
To be a tough critique, I spotted a few things to fix or can improve on.

HR: http://img661.imageshack.us/img661/5259/HMq4E4.jpg
-1 The rear wheel is not erased properly, I can still see the floor from the old image
-2 The bottom of the diffuser and the inside of the rear wheel arch is different, try to match the blacks

-3 Missing door line, but if the car has no doors then I wont argue
- 4 the area above the arch and the window needs a bit more detail as it is looking too toony/ flat
-5 Try to never have vents hollow and looking empty. Always put some inter cooler, mesh, air piping to fill out the holes if it is realistic!
-6 Your brushing is nice and smooth, but because I can see the hood from the original 350Z and it is noisy, you need to match the paint. so I'd run a Noise filter @1%
-7 Make sure all your vents are lined up together, easiest way would be to make the vents once and just duplicate it 2 times,
-8 Your sticker placement is good, but it is too sharp comparing to the rest of the car, I would blur it a tiny bit to match your soft brushing
-9 I love the lip, but the 2 sides dont match, on the left it is a very curvy (hugging the front bumper shape) but the right side it is sticking out, so I you need to extend the left side or erase some of the right side lip
-10 No more 7K high res, its killing my computer!!!
Really though, this ia a big step up, great work mate!
To be a tough critique, I spotted a few things to fix or can improve on.

HR: http://img661.imageshack.us/img661/5259/HMq4E4.jpg
-1 The rear wheel is not erased properly, I can still see the floor from the old image
-2 The bottom of the diffuser and the inside of the rear wheel arch is different, try to match the blacks

-3 Missing door line, but if the car has no doors then I wont argue
- 4 the area above the arch and the window needs a bit more detail as it is looking too toony/ flat
-5 Try to never have vents hollow and looking empty. Always put some inter cooler, mesh, air piping to fill out the holes if it is realistic!
-6 Your brushing is nice and smooth, but because I can see the hood from the original 350Z and it is noisy, you need to match the paint. so I'd run a Noise filter @1%
-7 Make sure all your vents are lined up together, easiest way would be to make the vents once and just duplicate it 2 times,
-8 Your sticker placement is good, but it is too sharp comparing to the rest of the car, I would blur it a tiny bit to match your soft brushing
-9 I love the lip, but the 2 sides dont match, on the left it is a very curvy (hugging the front bumper shape) but the right side it is sticking out, so I you need to extend the left side or erase some of the right side lip
-10 No more 7K high res, its killing my computer!!!

Really though, this ia a big step up, great work mate!