The highest pitch I've heard is Long tubes and:

1. Corsa Touring
2. SLP LM II
3. Magnaflow (I don't know what number)

Try the exhaust sounds thread and find what suits you best.
http://ls1gto.com/forums/showthread.php?t=115630

 

Whatever you go, the x pipe is a MUST for an exotic sound

 

Borla supposedly has the most 'exotic' sound, and that's what I ordered (and am waiting for). However, some folks have reported drone with other modifications, so better do your homework. The 2nd in line for me was the Magnaflow catback, and reportedly no drone with mods, so that might be your ticket. And it's A LOT cheaper than Borla. And yes, an X-pipe is a must to combine the pulses of both banks, and both systems mentioned above have it. Good luck. Car looks great already man. And with all those engine mods, it should kick butt too. Later.
JC

 

Borla, hands down.

 

Does someone make something that will take all of that burble out and just leave the high pitch scream?

So you're looking for something like this?

 

Exactly...

 

I'll look more into the Borla. I've had SLP stuff that was quite high pitch... would the Borla be higher pitch than the SLP LM1 catback? I'm also wondering if the X-pipe is going to muffle the lope of the cam...

 

Corsa Sport.

 

That exhaust I posted was something crazy like $6k, maybe more.

Its funny that you're trying to get all the highs out of your LS motor, and I spent 5 years as an E46 M3 owner trying to get lows out of my S54.

Maybe what I learned there can help you. All the cat backs you could try are probably not going to help you in your quest. There is a good reason for that. My own research found that the reason late model M3's sound so euro and shrill is because they have cats in the collectors. Short primaries terminating in 600cpi cats. That kills the low resonances coming out of the head and only passes the higher notes on to the muffler. I would think that anything you could do to duplicate that setup will get you the sound you desire. Probably using stock cast manifolds and having cats mounted as close to the flange as possible would get you there. You'd have higher underhood temps though.

 

There are two main items that the LSx motors don't have that contribute heavily to that F1/Ferrari sound.

First is RPM

Second is small bore/stroke.

You can probably get part of the way there with custom exhaust, but not all the way.

You might try to find a small custom exhaust shop that has been around for a while and see if they have any ideas.