I have used Summit on several ocasions and have been satisfied with their service most of that was back when I was building my 512, but I have to say I have been dealing with Jegs for over 35 years and have yet to have bad service or a problem with them, now I know that cannot be said by everyone but that holds true with summit also, the second best supplier has been Competition Products but their selection is more limited and chevy and stock car they still have treated me well on orders that I have put in with them.