1. My '96 GT burns some oil ...it's most noticeable when I'm idling for a few minutes then pull away or rev it - there's a cloud of blue smoke. But when I'm driving it is not noticeable. Question is - does this sound more like valve seals or piston rings? 2. Also, if I have to replace the valve seals, I'll do the PI headswap. Just wondered for those who have done it - how much did the exhaust note change? Was it a distinct difference or just slightly different? I'd imagine it would sound a little better after the swap. Thanks.