I think billzilla's info is bang on, with methods and modifications etc but his power figures seem optimistic from my experience...

Personally I would stick with the 16v engine and put the money in to parts. Exhaust, intake, cams and a standalone ecu would see you around 150bhp without headwork.

Check out the Billzilla writeup for a full guide on tuning the 4AGE and you'll get an idea for just how much work is needed to get 180bhp.

http://www.billzilla.org/4agmods.htm

You gotta move heaven and earth to get 180hp from a 20v. Same as a 16v.

If you dont want to tune the motor then 20v is nicer, throttle bodies etc. But the time and expense fitting a 20v could be put into the 16v you all ready have.. Either way, the wallet is gonna get hurt.

Hmm. I might use it for donor parts then for a 16v build. Ultimately you can run more interesting camshafts with the 16v as they are stronger. I've not seen a cheap blacktop yet lol

Most use the blacktop as it has itb's and no afm like the silvertop but if its just the motor your using then I can't see a problem. If I remember rightly the silvertop has heavier rods wich are better for turbo applications but not so good for N/A.

Myself personal preference would be hi ccomp16v haha Ive started down that route but if you are just wanting an easy 160 - 180 bhp go with the 20v but if you want to push for more you will spend the same sorts of money on either a 16v or 20v but obviousley you will have to pay the extra for the 20v conversion.

I might have a 20v silvertop coming my way. I'm contemplating whether its worth fitting in the car. Has any of you done the conversion and thought you should have just raised the compression on the 16v?