If you wire the bulbs so the H4 bulb has both filaments on it will be a bit brighter but there will be nasty glares all over. Im not sure if Silverstars are the brightest or not but they are know to not blow out as quck as piaa and such. I put alot of time in making a relay and stuff so I could use the h4 bulbs as high beams as well and it just isnt worth it. They dont realy get much brighter because when you have high beam bulbs you dont want the little cutoff shield. Look at the middle lights they have no sheild. This lets the light go everywhere rather the outer lights or low beams has the sheild which cuts the light off so you dont blind the shit out of everyone. if you have any more questions hit me up on aim mypreludesi92.