Originally Posted by
Davemurphy007
The vernier pulley on the exhaust cam is said to be one of the best 'bolt-on' mods you can do - potentially releasing up to around 10bhp. But for the best results it will need an hour or so's tuning on a dyno so debateable whether it's a bolt-on mod. Uprated coil pack and leads is a waste of money, arguably the same with the 67mm throttle body unless you are going forced induction (ST170 throttle body is already 65mm which is bigger than the standard 2.0 litre).
They're a very well tuned engine from the factory and quite difficult to get more power out of without drastic mods like forced inductions or ITBs. Most of the crap you can buy which would be reasonably good on the standard 2.0 litre won't make much positive difference on the ST170.
iv not long done the exhaust vernier and yes it is a great mod for the money if you can do it yourself.i full beleive its 10bhp quicker.
i havent had no rolling road set up, i just went for the general opinion of -6degrees retarded and it works a treat. i dont think a rolling road is needed as -6 seems to be the given rule so personally i wouldnt waste your money on that. on the st170 facebook club a guy had his set up on dyno and -6 gave him best results.