Who has the best price for the RS*R down springs for the G35 coupe, I think I will be going that route for my suspension lowering.

 

You had posted a previous question about wanting linear springs. The coupe RSR's are progressive front and rear, with 315lbs front and rear. The 350Z RSR's, only the front spring is slightly (one coil) progressive and the rear spring is linear, spring rates are stiffer at 345lbs front and 417lbs rear. The coupe version will ride better, but the Z version will provide better handling, depend's on what you want out of the springs.
And their front to rear balance is also different, the Z version shifts some spring stiffness to the rear, which will help reduce understeer or to some it will help rotate the car more easily.

RSR springs vs oem
Oem springs 314/342

coupe RSR 315/315 Front % 0+ Rear % -8%
shifts +8% roll stiffness to front

350Z RSR 345/417 Front % +10% Rear % +22
shifts +12% roll stiffness to rear

"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

So you would advise me to get the 350z version springs instead? Is linear better than progressive?

 

For handling, Yes Linear is better. But the ride will be a lot harsher than with progressive springs.

Twilight Blue G35 Coupe 6MT
Premium - Nav - Aero - Trunk Mat
Injen CAI