Auto_Sparky_WRX

hey im postin on behalf of a friend he recently got a 51 plate bug it had been sat for a wile because of a gearbox problem since he got it he has replaced the gearbox but since he has had it about a week of driving the engine light came on, the code is "system to lean, bank1 sensor 1" we are both auto electricians workin at the same place so we pluged it on the diag machine n the short term feul trim bank 1 sensor 1 is peged at 25% all the time indercating a air leak, he has a nagasaki bag'o crappy induction kit (same as i hav on my 52 bug) he has a bov but we ruled that out by puttin the standard back on, we hav changed all the breather pipes goin from the inlet pipe to the inlet manifold, 2night we changed the inlet pipe for one of them "samco" pipes off ebay,when we removed his where it joins the turbo was perished so we thought we cracked it but... still no joy there is a very high pitch noise coming from behind the inlet manifold nearside but we had the intercooler off a few times n there is only a couple of pipes there 1 being the rocker breather.

if any1 can help or post pics of the breather system

cheers for readin sorry about the spellin.... dont need 2 spell to work a spanner lol