Just thought I would share my experience on the engine builder I used to rebuild my EJ20Y when the big end bearings failed in the summer of 2012.
His name is Ashley Wilks and operates from a small unit in Shipley West Yorkshire. Ashley was very easy to talk to, you can discuss any concerns with him and he offers recommendations for the best way forward for your specific issues. He was very enthusiastic, couldn't help enough and gave me a great sense of trust - just what you want when you hand over your 'pride and joy' to have it's engine rebuilt!
To cut a long story short his standard rebuild includes new pistons & rings, new main and big end bearings (I went for ACL Race bearings) and all new seals and gaskets etc. I went for "like for like" new pistons which are more than up to the power levels the engine is producing.
In addition to the above I also went for stronger 'Taper' conrods (as used in STI's as they are good for at least 400 BHP) because the standard 'skinny' rods are a known weak point in these engines. I also had a new oil modine (because of the big end failure there may have been little bits of metal particles lurking around and as the modines are sealed it's impossible to guaranteed they are clean) and a new water pump just because the old one had done 95k.
I have now been driving the car for almost 10k trouble free miles and she is going like a train with no issues.
Ashley's prices were also the best by far I had come across and so if your big ends fail (or you need any engine building doing for what ever reason) give him a call - you may be pleasantly surprised!!
p.s. Ashley also fitted a new clutch and swapped the gearbox and rear diff at the same time as the engine rebuild all for a very competitive price.
Hope this helps some of you guys in times of need!