i am looking for a quieter mod for my .223 I have a spartan third eye at the minute and was wondering if there was anything quieter?
You could try a Third Eye Spartan

Dave (baldie) did a review on them
here ..... he might be able to assist.... never heard of them myself...
Without knowing the sound reduction abilities of the Spartan it would be hard to say what would be better....
I have an Ase Ultra

for my .223 / 5.56 rifles, a Wildcat for my .308, couple of SAKS and Parker Hales for my rimfire.....
All work well enough but without running them alongside each other it would be hard to say which was better for noise reduction...
Why do you want to change from the Spartan? Is it lacking in some department?
The spartan isn,t the quietest mod on the market, but it is light, which is why many fit them to stalking rifles. I dont fit them to anything bigger than a .223 these days.
I sell more ASE Jet-z compacts than any other mod these days. They are not particularly light, but they are the quietest mod out there, and are built to last.