Even with brand new big dollar parts things still fail. I think on calaisturbo one of the big name vl cars lost a 3.2 stroker on the dyno.
I lost a brand new engine from my previous mechanic not being able to read "in and out" on my oil cooler relocation kit the result was a bent crank and stuffed bearings.
My 33 would have made more power if I had a better exhaust, 3.5" just isnt enough...