Doean't a crack in the manifold make it backfire and sound really tough? Lol.
My mate had a Cressida, got a stupid 5" straight pipe through it... the manifold had a crack in it, so it backfired louder than gunshots. He went into the Marion undercover park one time and started revving the shit out of it... flames popping out and it sounded like bombs were exploding... then 2 undercover cops walked out and fined him for excessive noise hahaha.
But yeah, his was just a crack in the manifold... letting air in, making it backfire.
But it sounded so f**king tough hahah