I was wondering if I should of emailed them and told me to send the 5's. They didn't ship yet maybe I will do that. I doubt there's any difference between the two. Hmm. So going back to the whole 245/40/20 thing...think I can swing it with those lowering springs. I can't really tell how much room was left in your wheel wells from the pics you put up earlier in the thread.
EDIT: I shot them over an email about this and this is the response I received...
"Hi Craig,
I am not sure who has informed you of that but they are wrong, There is only one Insignia engine that is not 4 cylinder and that is the VXR (2.8T 4WD) and they have completely different springs to the others.
The springs you have sent me the link for are for the 1.6, 1.6T & 1.8 that we have over here. I believe that Buick doesn't use these engines in the US. The UK has become obsessed with emissions and fuel consumption in recent years unfortunately and we have some smaller engine cars than you guys in the US. Obviously the smaller engines weigh less so that kit is for them. I believe that the smallest you guys have is the 2.0T so the springs you have ordered are correct.
They will be with us here on Monday and we will then get them shipped over to you. I have had this conversation with another customer from New York State who has ordered them for his 2.0T Buick Regal as well.
Kind Regards,
Graeme Johnston
Managing Director
GNJ Motorsport Ltd"