Jeffrey Schwartz <schwartz.jeffrey@gmail.com> wrote:
> Can one build a TL13 "Ultimate", then apply the +2TL "Modified" on it
> to bump up to TL15?
> Which would make it even smaller, more efficient, but best of all
> change the price from x4 to x4/2 ?

While I can't see anything in the rules  that  explicitly  covers
this, I don't think so.

The TL stage effect isn't supposed to be some 'process' done to a
device's design, it's supposed to  represent  how  much  a  thing
varies from the  reference  TL.  Different  names  for  different
amounts of variation.  Look at it this way, if  you  could  stack
'Experimental', 'Prototype', and 'Early' you'd  have  a  combined
-6 TL modifier that would allow for Bronze Age spaceships!

So the RAW says an 'Ultimate' thing is the ultimate expression of
that thing and you can't get better than  that.  Of  course,  you
could argue that the scale should be open ended in  the  positive
direction ... but any houserule levels beyond 'Ultimate' would be
extrapolations, not merely additive.

Just my Cr0.02, IMHO, YMMV.

Regards
Hemdian