Thanks for the reassurance...I did notice a couple of things yesterday.....I kicked down once I'd got on the motorway to overtake (and hear the whoosh noise) and it seemed to redline in neutral then went into a lower gear - that enough has convinced me it needs all the oil out and the right stuff going in asap.
I also noticed a rough idle upon starting, which went away when I tapped on the accelerator a couple of times up to 2500-3000rpm. Also the battery light flashed for a second so something to investigate there. I know the car went through several batteries before I bought it, but I put that down to it sitting on the owner's drive for years unused, thurs and fri I've been driving around 16 miles a day to work and back. If it happens again then I'm putting battery and alternator on the check out list.
The garage swapped in the induction kit I brought in (bought it, changed my mind, told them then they fitted it anyway) but luckily I still have the old parts in the boot so that will probably get out back on.... plus it has an aftermarket head unit and cd changer in the boot so I'm wondering if that could have caused the battery issues
Either way they're going in the near future!