ok here's the deal, I imported a jdm Subaru impreza wrx type ra year 2000 from japan, when the car arrived, I drove it for 2 days, but hardly past the 4000 rpm, the 2nd day allot smoke came out the exhaust, and the engine started to sound like there were screws inside the cylinder, so I parked the car and it stayed there until I got enough money to fix it, my car came from japan with a ej207 engine in it. when I decided to pull out the engine I found that cylinder number 4 head a broken piston in it, and it damaged the sleeve of the engine blokc, last week I bought a ej206 from a guy, and I swapped the engine in it, using my intake manifold and my turbo ect, so basically I used my wiring and everything, because the ej206 was from a legacy B4 and as you know they are twin turbo's ect,, today a started the car up, after warming up, the car started to sound like something is maybe broken in the cylinder number 4, and the cylinder number 4 is the same cylinder number that I found a broken piston in on the other engine (ej207), and also today the car started smoking very lightly from the exhaust , the sound is more in the 1000 rpm to the 3000 rpm,, @ 4000 rpm the sound is gone,, hope that's enough info.. thanks in advance for the help