Can I build a...
 

350 single turbo rwhp car that would run not only quickly but reliably as well?? I would get it dynoed and just kept at the same boost setting...would I be able to create a monster that could run 120-150k miles off a rebuilt street ported motor?

Yes, but it might take you a few motors to get there. ;) Buy reliable stuff, give it lots of cooling attention, and tune it for reliability rather than dyno bragging rights. You might be able to make 350 reliably on your first try. I am shooting for 400 reliable RWHP, but I doubt it will last 100,000+ miles. 50,000 would be great.

-Max

My friends motor runs the stock twins (370 rwhp @ 15 psi) His motor lasted 110,000 miles.

Did he crank up the boost at 109,000 miles to get the 370RWHP dyno numbers? ;) I am half-kidding, but I don't think any car with the stock turbos and 350+ RWHP would last 100,000 miles making that much power the whole time. And to even get 370RWHP with the stock twins at 15 psi, you need to have a lot of supporting items. Did you ever see the dyno chart, or was the power level just an estimate?

I am not trying to be needlessly argumentative, but I would be very surprised to hear of any car running more than 100,000 miles making 350+ RWHP the whole time, let alone on the stock turbos.

-Max

It all depends on how much your actually pushing that 350hp, If your always on it there is a better chance of blowing it... If you baby it till the power is needed you should be able to make it last that long with good cooling as states earlier and frequent oil changes...

maybe shoot over the 350rwhp figure, but then damper it back down to 350, you can make more, but you rather go for reliabilty