As far as modding the existing engine, I would do that and get more power out of it, as opposed to be, no offense stupid, and go with a "better" engine. There are hi-performance parts that Import Performance Parts sells like a TOGA High Volume Oil Pump, Valves, Rod Bearings, Main Bearings, Gaskets, etc. You can also make use of universal parts and adapt them to fit. If you check with K&N Air Filters or Tornado air filters, they both should have a hi-performance filter for your application. As I've been told, Weber has a 32/36 DGEV carb for $400 or you still could go with dual sidedraft carbs like someone on YouTube did with their Toyota 4AC engine. Headers for the engine are available, but you may have to have them custom-made at this point. Pacesetter also sold headers for the 1.6L RWD 4AC, but those will fit the 3AC as well as the ports are all the same for setup, except the head shape. The links to everything are as follows:
IMPORT:
http://www.importperformanceparts.net
K&N:
http://www.knfilters.com/search/appsearch.aspx
Tornado:
http://www.tornadoair.com/carbthrottlemeasurement.htm
Weber:
http://www.redlineweber.com/html/app...ide/TOYOTA.htm
Pacesetter:
http://www.pacesetterexhaust.com/
pacesetter doesn't stock the headers anymore, but here's a link as to what I think they looked like:
http://www.streetperformance.com/par...1-72c1095.html
They also had a Monza performance catback exhaust system for the wagon:
http://www.sfxperformance.com/parts/PAC881413.htm
I know back in the mid 80's HKS sold an intake manifold that could adapt 40mm sidedraft carbs. They also sold a direct bolt-on turbo kit known as the HT10. I believe HKS of Japan was the only one to market this, judging from a japanese-language book of mine that goes all into cool tuning and dress-up products for the AL20 and 21 Tercel/Corsa/Corolla II, buth a lot of it should also apply to the AL25 4-door 4WD sedan and the AL25 wagon as well....
