I never said use an American V8... Audi, BMW, Toyota, etc all make V8's do due diligence and find which engine comes closest in size and sound. Then add the correct combo in the exhaust parts and you'll get very close if not dead on. These engineers are not magicians that wont give up their trade secrets. If they can do it so can we.

The size and configuration does matter... The only reason the V12 seems to sound the least accurate to you is simply because you have not come across anyone that has done it right as of yet. The guys that have used the V12 didn't complete the exhaust system conversion. They may use the Lambo muffler but not the pipes, the headers or the cats or vice versa, which makes a big difference. Ask any performance muffler shop how to tune your exhaust to achieve a certain sound and they will give you a multitude of combinations. Do you see how big the Lambo pipes are? Then look at the size of the tail pipes. All the gases that fill the big pipes are forced through the smaller tail pipes and makes a higher pitched sound. If the V12's you researched don't have this set up, then that's one part of the sound that will be missing. However, because the engine ports are not the same size and shape as the Lambo, different size and length pipes may need to be used. I had a set of cat backs on a 350z that made the cars sound very close to the Lambo. A V6 is half of the V12, it will work the same way. I've researched other sites with posts from the 90's, and they were saying that the V12 would never work in the Diablo kits. This was their way of thinking until someone ignored their advice and tried it. And guess what?... It worked!!! Don't ever give up on what you want because others either failed at their half hearted attempts or just talk negative without even trying. If you really want that Lambo sound, follow me, I'll find where it's hiding. 

TTT

Those of you who are talking exotic engines (Not BMW 12) you better have a lot of engineering knowledge, plenty of time oh and lots of cash.  Once you step into that realm you are on your own.  You will be fabricating everything.  Exotic engines will need a adapter for the transaxle, swapping out an engine you may need a larger cooling system, using CC system you may need to have a chip burned it goes on and on.  this doesn't only apply to drivetrain either.  I am currently working an CC electronic steering system for my build which will alter steering effort based upon vehicle speed and steering wheel effort.  The build required a different rack, then a different steering column then new joint, steering shafts, sensors and ton of time, you get the idea.

Have any of you guys started your builds yet, or is this just shop talk?

Those of you who insist you can duplicate the sound of a lambo V12 please post a recording when you achieve the correct sound for all to hear.


Mike

i just want my car not to sound like a huge muscle car

As long as mine sounds exotic, I don't really care how close to Ferrari it gets.
I do care about the sound, not as much as the other sensory aspects, but the reason I'm building the car in the first place is I like the way it looks.  I also like the way it sounds. 
I don't really care if it meets the all-out-race performance specs, as I don't drive like that anymore anyway. Never really did.
I'm into driving a good looking car that sounds good and has good performance too.
If the kid in the Z-28 wants to race stoplight to stoplight, I have NO problem letting him win, No contest.  I usually just rev it up and pull away at a normal speed.  Call it "past the mid-life crisis" stage, call it maturity, call it responsible, call it whatever you want, it just doesn't matter anyway.
If it were not for the look/safety/and mechanical wear issues on the bearings, I'd fore-go the wide track stuff and just use wheel spacers as I don't do "burnouts", skids, etc. unless it's an unforeseen emergency.
I guess my over the road trucker experience changed my attitude about driving.
The last car I bought was a Cadillac sedan deville.  I prefer comfort and looks.

Why are limiting yourself to a Chevy V8? If you want to come as close as possible to the f car sound, explore all V8 options.
This is the point where you step out on your own and be your own man. These reasons for not going this route sound like the things your parents would come up with to scare you from of moving out of their home at 18yrs old to start your own adult life. If you have what it takes to buy the kits, then don't sell yourself short on the sound if the sound makes a difference to you. Yes you may have to pay extra to accomplish this. You also have to pay extra for EXTREME's Murci kit compared to the G24 kit. And there seems to be quit a few people that are willing to do so... because it looks just like the real thing. To me, every part of the build counts towards the end results. And if it takes a little longer to complete it properly in my eyes, then it will just take longer.
I haven't officially started the building of my kit because it's not going to be ready until sometime in Feb. 09. I've acquired to second position for the 12 AD-LP640 kits for 2009. However, I have been collecting some parts and research for the build. I truly believe that I can achieve the V12 roar of the Murci, and when I do I will definitely share that info with all that would like to hear it. No disrespect to the older or more experience member on this forum. But I believe with some of the younger members, building a kit isn't to show everybody "look what I've done." But more along the lines of, "look what I've got."


Just my thoughts...

TTT

Then it's time for a transplant.

I saw one with the rods and pistons at the KitCar swap meet in the spring. I think it was about 11K or so. You still needed to get the camshaft for it. Some of the short track guys have them as well if you want to look there.