The jspec cam are slightly more agressive than the 03 cams, and will result in modest gains (around 8-10 hp on the dyno I think). Without really getting into it, this is done through different combinations of lift and duration (higher lift, keeping the valves open longer, etc.)
They should drop right in, but it is not a trivial install. It is a fair amount of work. Between the price of the cams and the install, a lot of people think it isn't worth the time and money for the amount of power gained. If you are going to the trouble of doing cams, you might consider interprep or paeco. They have cams that are more aggressive than the ZE cams and will give higher gains, but will probably be a bit more work and will idle faster. Shims are required.
Order some interprep street cams for $600USD plus $104USD for shims then take them to A-spec and they'll charge you probably like $400CDN to install and you have yourself something like 14-16whp extra which is completely hidden other than the 900rpm idle. You wouldn't have to tell anybody about it meanwhile you would dyno at a little over 150whp which is similar to installing a Jap spec engine without ECU.
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