My main source of dissatisfaction with my G37 is that I sit too high in it. I'm 6' 5 1/2" tall with a 36 1/2" inseam, and my hair brushes on bumps and on bad hair days. My car is an '09 X with sport seats.
I performed the mod on the seat lowering bolt that others have mentioned and was unimpressed. If I got a half inch out of it I'd be surprised.
So, I took the seat out of the car and had a look at it. I performed the mod to get rid of the steel reinforcements for the side bolsters. I just cut them off with a dremel and stuffed the inflatable bags back in - nothing fancy. I was very pleased with this mod. I hadn't realized how much those things were bothering me.
I then turned the seat over and unhooked the seat springs from the steel bar that runs across the rear of the seat. There's a white plastic piece that goes between the spring hooks and the bar that I took out. They essentially just hang down in the back now, which is probably OK but I zip-tied the top of the hooks to the bottom of the bar so they wouldn't rattle. I'm not sure if that's necessary. I left the springs attached in the front of the seat.
This made a huge difference. I now sit much more "in" the seat than "on" it and got at least an inch of extra headroom out of it. This mod is also completely reversible if you don't like it.

 

Thanks. Pictures would have been great.

 

Seconded. Also, what's the common lowering mod you did originally? I haven't heard of it and I'd love another half inch.

 

https://www.myg37.com/forums/body-in...ml#post2249587

 

In this photo you can see the hooked ends of the springs relocated from being hooked over the top of the horizontal steel bar at the back of the seat bottom to their new location zip-tied beneath the bar.

 

That's clever!

 

That's what she said

 

Here's the link for the side bolster modifications if anyone's interested:
G37 Seat Modification by Gary Godish | Photobucket

 

Sweet, thanks!

I knew that was coming as soon as I clicked post lol.

 

As an update, I've put several hundred miles on the car since performing this modification and am still very pleased. The combination of removal of the side-bolster bars on the sport seats and sitting an inch or two lower has really improved my comfort and my sense of fitting properly in the car.