Will dual ground platinum plugs really make a difference in a Lexus? Or will single ground AC delco plugs or another brand work?

Just use the correct Denso or NGK plugs. If you want performance then use Denso Iridium and change them every 30,000 miles
http://www.densoiridium.com/index.php?flash=1

what do you recon to these as i am needing new ones

www.promax.uku.co.uk/spark.htm

thanks

here is the link again
sorry

http://www.promax.uku.co.uk/spark.htm