The idea with fingerprinting is that you know an ip address that seems to be a computer. Now you want to know the brand (Solaris, HP-UX, AIX, etc). Once you know that it is, say, a Solaris box, you then try known Solaris weaknesses. Since, by default, Solaris uses 255 as a TTL, if you see a TTL of 255, it might be Solaris. The trouble is that 255 is the max for TTL, and in the 90's a few OS's got burned with TTL's that were too small. My impression is that most vendors cranked TTL up to the max. If you really feel the need to fiddle with TTL, keep it high. 155 is not too bad. You might regret 55 though.
Changing the TTL is not going to close a port. You're trying to make them think you have a Linix box or something. That way they spend all the time hitting you with Linux attacks rather than Solaris attacks.
This is a bunch of jive if you ask me. Keep your Solaris box well patched and then you should not care if the bad guys know it's Solaris. Security by obscurity does not work. But here is a
another opinion.