Because the V6 in it is frikken tight enough as is! I couldn't imagine anything even slightly bigger in there!
I've been working on my SVT for about a week now, on and off: I dropped an upgraded the trans and I'm installing the Street Flight turbocharger kit.
IT'S A ABSOLUTE BIATCH TO WORK ON!
You need hands of a child that have the strength of Arnold Schwartzy and wrists that bend in any direction as it is, let alone with anything bigger in there!!
What's got me miffed? Two words - EXHAUST MANIFOLDS