It really depends mate, the health of your engine and the tune will play the biggest parts, a good tune will be fine for stock internals and could possibly run decent boost ... but thats were the health of your engine comes into it.
Well like the lads said all depends if the engine is in good nick,
Im runnin 238-bph at 1 bar on high boost on normal internals runs sweet as a nut, I wouldnt push any more out off it tho.