I think the majority of people on here know that when you put an aftermarket exhaust on the Z there isn't enough back pressure to hold the rear turbo seals in place so you end up with turbo smoke. (happened on my 200 actually but cured it to some extent with a one way valve in the breather pipe).

My question is, is this always the case 'cause the car I was meant to be looking at (which broke down) today had a super dragger on but apparently no smoke. I wondered if it's 'cause it's only cat back?

Catback exhaust doesn't usually cause too much trouble. It's when you lose the cats that any turbo seal problems will surface.

Cheers Coogs. Like I thought.