FWIW, a 2.5L engine at ~14PSI will put out the same amount of exhaust as a 5.0L engine. I was under the impression the Bosal exhaust was 2.5" ID pipes, then split to two 2.25" ID pipes. Plus, they are straight-through design mufflers/resonator.
If a 5.7L engine is fine with a single 3" (Camaro, Firebird, Corvette), why can't a roughly 3.7L engine be fine with a 2.5" ?
You also have to look at the exhaust components in front of the cat. Is the smallest piece equivelant to a 3" ID pipe? Still keep in mind the velocity factor.
Oh, and the stock Y-pipe sucks
