Hi,

F18B is a SOHC and mods for it are going to cost you more... F block appears to be rare... However, to get a bit grunt and power, try with a good size, double cone air filter. Regular maintenance is a must, and use iridium plugs... Nice bore helps too... If you take out the originally supplied air filter box, you will get more than enough of space for doube cone. Make sure to create NICE FLOW of cold air. I used the secondary box, underneath. I punched a hole in it just large enough for 3' air duct. The inner pieces in this chamber i just cut of with a scraper. It was amission, but it works. Especially when cold outside. Use unleaded 95 or 98 instead of 91. Much better burning.