the site says this;
"Optional Springs for 38mm and 35mm-HP (only - will not fit standard 35mm)"

what's the difference between the two?

if i want to get their springs i would have to buy the HP one, also how do i tell i am purchasing the HP and not the standard one?

edit:
http://www.lightningmotorsports.com/tialsport.htm

 

Before you go and purcase a Tial W/G, take a look at Turbosmart Ultragate 38mm. It is smaller then the Tial 38mm but will flow 20% more. It is made entirely of 253ma stainless steel which will never rust or corrode. It won't even collect deposits when race gas is used. The tial is sand cast and will rust on its backside. The ultragate is investment cast, which is more precise, and it will never rust. Plus, the ultragate already comes with all it's springs.

 

what's the lowest psi spring do that is available? on the website it says 9 psi, i think.

 

but then again for the price of the turbosmart ultragate you could get the vband 44mm tial