You are supposed to "lap" the two halves if they dont fit tight enough to seal.

Pretty simple, get very fine wet/dry paper and a perfectly flat stone or glass work surface. Sand the mating surfaces. Clean them SUPER good before resembling, pop test, adj, test again and install with new heat sheild.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)