yes I think thats right, he's not trying to do anything dodgy, just wants to advertise a swap and not risk getting the car sold for a ridiculously cheap price. Some people just say 'do not bid' but I suppose this is safer.
Fair enough but I also put a K&N on my rev 4 and it made quite a difference - definately more throttle response, without losing any noticeable torque - the torque is crap anyway low down so I'm up for gaining top end power!! The difference in engines between your '91 and my '98 means they proba...
I would be tempted to stay with the stock induction and not got too mad on the exhaust, or you will end up losing loads of low-down torque. I drove my 1991 Mk2 (NA) with a K&N for about 12 months before getting rid of it forever - a lot of noise for little or no improvement in *useable* performa...
I really wouldn't bother trying to use rev 3+ tech to mod your car. It's just as fast, if not faster. And it can steer sharper (if you can control that back end).