I'll tell you this about the fuel o-rings and  the very well made ,METAL
Subaru fuel rails........they last perfectly in my experience., I don't
worry about them much. - the o-rings. 
They could barely seep at the most usually.  Or if someone leaves some
screws loose, of course. 

I priced ALL the fuel seals for a six cylinder SVX engine at the dealer once
- all injector seals, all fuel rail  seals etc.  - 300 bucks total !! 

But you almost don't need them, it's not like they are weak. But that's how
'good' they are ! if price means something,
And OE Subaru parts........they don't get better practically.
Once you buy an expensive OE part - that's basically it - that part is good
for 10 years or so. 
Btw.........sorry to go on ..
Once a good Subaru conversion is REALLY dialed in right .......it just stays
that way for years sometimes. Extremely STABLE that way. 
The systems are at least twice as precise and strong as than the ones on a
waterboxer, plus it runs twice as good, at least.

A water boxer holds a tune and set up for a while.........but not like a
refrigerator, like a good Soobie can. The can work really well, just
endlessly, and reliably,
And that is not to say home converters don't struggle getting a consistent
idle or whatever - they do.  

But once it's ALL dialed in exactly.........it STAYS that way baby, unless
you drive the snot out of it, or put bad fuel in or whatever. Or didn't
build the exhaust very well say.........but DONE RIGHT - they are so stable
and consistent, they are boring that way almost . They can JUST WORK....like
a fridge at home.
You NEVER even think about your fridge  except to defrost or clean it.
A good Soobie conversion can be that consistent, quite, and STABLE, 

-  Unlike this pc with MS software that I am about to dump for a Mac. It's a
new Dell even. - XP though ......but I can't imagine Vista is better - MS is
truly the Evil Empire for sure in my opinion. But thank goodness we have
this way to all interact ! 
I'll try to be more quiet. 
Hey - I trimmed the post didn't I ?  - LOL ! 

Scott
Vanagon Engine conversion specialist.
www.turbovans.com