I like Bosch -- Denso in a 2-cycle 250cc
My NA is 15 years old, and I can't tell you if Denso will get you 9 more HP, but I switched to the Bosch +4 and there was a definate improvement for only about $25. Was it just new plugs? I would like to see some dyno tests on the Densos on a real car.
On the Denso page at
http://www.denso.co.jp/PLUG/iridium-e/q15.html
they did their "power" test on a 250cc 2-cycle engine. I don't know if someone extrapolated to get 9 HP from a Supra, but I would think an oil-gas mixture has different burn aspects than an all gas. In fact a 2-cycle plug might be much worse in a 4-cycle engine!
Just to give another view, you might also check out this site, which while it refers to SplitFire plugs, might be appropriate to almost any.
http://www.ftc.gov/os/1997/9702/splitfir.htm
My NA is 15 years old, and I can't tell you if Denso will get you 9 more HP, but I switched to the Bosch +4 and there was a definate improvement for only about $25. Was it just new plugs? I would like to see some dyno tests on the Densos on a real car.
On the Denso page at
http://www.denso.co.jp/PLUG/iridium-e/q15.html
they did their "power" test on a 250cc 2-cycle engine. I don't know if someone extrapolated to get 9 HP from a Supra, but I would think an oil-gas mixture has different burn aspects than an all gas. In fact a 2-cycle plug might be much worse in a 4-cycle engine!
Just to give another view, you might also check out this site, which while it refers to SplitFire plugs, might be appropriate to almost any.
http://www.ftc.gov/os/1997/9702/splitfir.htm