I have the SHO Shop Y and Bassani on my 3L. OEM exhaust manifolds and resonator tips remain in the mufflers. Little raspy when cold (but I think that I have a loose clamp so I'm checking that next weekend). Drones like mad at 3000 RPM until secondaries open. Definitely VERY throaty and intimidating, a lot deeper than the 2.5s I have heard with it on.
You might want to look into a bigger TB to go along with the 3L. 65mm from a 'Stang or SHO Shop's 63mm (bored out SVT TB). SHO is a little pricey though.
This is a little off topic, but what do you plan to do about A/F? Mine is compensating as best it can under non-WOT, but at WOT it is WAY lean. Food for thought ... I expect to receive my Mallory adjustable fuel pressure regulator this week. I'll be bumping to 55 psi (with 19pph injectors) IF it works out. Appears I am the guinea pig on this one. Keep an eye out - I'll post my results as at least 6 people have asked about it.
