25w 8ohm resistor, I wired the leads one to the (+) which I think was white, one to the (-) which was black

 

I spoke to my local Evo/Ralliart tuner and they said they cant change the current values to keep the lights on. So i did a simple mathematical analysis on what we are dealing with, just so everyone understands why resistors are necessary.

We have two 21W Halogen bulbs as stock. This equates to 42W combined power.

We can calculate using simple formulas the current draw from these bulbs.

P=VI;
Therefore I=P/V >> I = 42W/12V = 3.5A

This means that the computer is happy with a current draw of 3.5A.

An LED light, say a CREE 16W lamp (32W combined) will draw..

I=P/V >> I = 32W/12V = 2.667A

This means we require to compensate for (3.5A-2.667A) .833A in the form of a resistor, and also means we have (42W-32W) 10W of power to dissipate in the resistors.

V=I*R;
Therefore R=V/I >> R = 12V/.833A = 14.4 Ohms

During my installation I found out that the computer is happy when one LED and one Halogen lamp is installed. We can use this information to save some power.

I = P/V = (16+21)/12 = 37/12 = 3.083A

Therefore the difference between current draw for two LED's and the combination now becomes...
3.083A-2.667A = .416A

This means the resistance value we require is..

R = V/I
R = 12V/.416A = 28.8 Ohms with a power rating of 5W.

I haven't yet tested this out but hopefully will give some people an idea on what is going on electrically.

 

To sum things up.

The computer should be happy with a resistor value of..

Approx 15 Ohms with a power value of AT LEAST 10W (Recommended 20W)

OR

Approx 28 Ohms with a power rating of AT LEAST 5W (Recommended 10W)