OMG dood DreamRide material...
Hop over to ACNA message boards and get some real feedback from Aurora owners.
Ok, lets focus on some real issues from my experiences. I have driven the "fastest" factory L67 in a Regal and my Regal owner friend drove my car...it was no comparision the L47 (Aurora 4.0) despite having 20 ft-lbs less tq, felt stronger, pulled harder at wicked high RPM, shifted nicer and felt like it had more..."je ne sais quoi" (his words)
The market for Aurora engines is not as diverse as the L67 market but its a race bred engine (IRL leagues..big winners in the late 90'*) it was also used in the limited edition Shelby.
Anyway, the fit and finish of the Rivi and the Rora is the same, dood its the same G-body chassis and it shares a LOT of components ( I have the FSM'*) braking power, etc is all the same I would think.
It just comes down to what you want more...4.0L Aurora 32V all aluminum V8 with 250bhp and 260 ft lbs tq with 3.71 gearing in the 4T80E or the familiar L67