Don't be so quick to say S13 and S14 studs are the same. I had a lengthy conversation with an application engineer at H&R a while back when I ran into problems with my studs. The S13 uses a knurl diameter (part that presses into the hub) that is the same for all wheels. The S14 studs have a different diameter knurl for front and rear. So that right there tells me they are not interchangable. I would investigate further before you drop $130 on something you can't use.
Ryan
P.S. If it was my money I would go with the Nismo studs (I actually ended up using the Nismo's when my H&R studs didn't fit properly.) and get the spacers from
Wheel Adapters. They are very reputable and offer competitive pricing.