Allow me to bother with an idea.
Please list the weight of the wheels used by you.
The wheel is the hardest part of the drivetrain and transmission.
The power that matters is to wheels.
A light wheel vehicle dynamics help.

Let's start with the factory wheels!

I know that the factory wheels ( Enkei 18x8.5J ET38 ) have 10Kg = 22Lbs.

 

Wedsports tc105n 18x9.5 17.9 lbs

 

WedsSport tc105n is a good option.

For another dimension:
18x9j et35 7.7Kg = 16.94Lbs

Would there be some interesting options.
Volk TE37MAG Blue Edition 18x9.5 5.9Kg=13Lbs (probably the easiest)

The second place is occupied by:
Boddy Club Racing P1QF 18X9J Et35 6.7Kg=15Lbs

 

duble

 

I really like the WedsSport tc105n, but kinda expensive, but they look great with concave design.

 

Reliable + Cheap = Not Fast
Cheap + Fast = Not Reliable
Fast + Reliable = Not Cheap

 

Your volk weight is off by about 5 pounds. The mag edition te37 in 18x9.5 weighs 17.2 lbs or 7.8kg.

The weds are 17.6 for 18x9.5 and 17.0 for 18x8.5

 

TE37 are normal weight.
Only TE37MAG are very light.

 

er, no. TE37MAG @ 18 x 9.5 is 17.2lbs. Standard TE37 in the same size is 18.3lbs.

 

I have TE37's in 18x9.5 on my car right now and they weigh 18.5 lb. on a postal scale, so your numbers are off. Magnesium is light...but not that light

 

Volk TE37 MAG (magnesium) are removed from production.
Buddy Club P1 Racing QF also no longer manufactured.

There are lighter wheels but the prices are astronomical.
They are made from unconventional materials.
Not occur in large numbers. No right to use public roads.
There are even some carbon models which weigh around 3kg about 6.6Lbs.
Best is 2.6Kg ...