head clicking noise after rebuild

Hi forum.

i am in the process of rebuilding my X3's alpha engine (1.5l dohc) for turboing. I changed pistons to lower comp ratio and had some work done to the head. After finally starting the engine i had this wierd loud clicking noise in the head... i have been driving the car for three weeks now and the noise kept reducing slightly however now it seems it stabilized with this constant ticking. Still louder than before the rebuild. I wanted to consult with you ppl maybe you can shed some light on the subject.

the head was ported, polished, resurfaced and i also had the valves changed to ferrea stainless steel valves. The valves had to be engineered to fit the accent head as the closest i could get when it comes to size is the toyota mr2 turbo valves.

I talked to the engineer which worked on the valves and head.. he told me that this is normal when it comes to ss valves.. he explained that the material is tougher and heavier than stock so it makes some louder noise. however i am not convinced so i am checking with the experts on this forum..

any answer will be appreciated. If you require more info i will try to provide it but right now nothing comes to mind.

thanks