4" thottle body

[kglowacky]

I bought this LS 1 off ebay . All good but need some help on a cold air intake system. It is a 2001 LS1 out of a Firebird. It has a 4" Thottle body inlet. The maf he sent me is a 3.5" opening on both sides. I am assuming there is a step down boot off this throttle body to 3.5: Has anyone have this on their build. I bought a 4" cold air kit that needs rubber adapters that really just don't seem to hold a clamp around the maf . If the 3.5 MAF is correct does anyone sell a step down boot??? If so then I will buy a 3'5 cold air intake and be done with this . Thanks