I'd have to say that anyone who plans on installing valve springs is planning on building up the top end, as well as, the bottom end of the engine, which in turn will produce a significant horsepower increase. Will it be adequate against a 250+ horsepower V8? Or even a 250+ horsepower V6? I'm not sure, but if you take the weight of a 4 cylinder compact into consideration, you may have a pretty respectable car, for what it is. You see, I have a '99 Mustang, but I decided to go a different route because once you start adding forced induction and swapping internal engine parts, you WILL break things on the car. Then, you have to spend more money to replace the broken parts because of the HP/Tourque increase. However, you wouldn't want to replace those parts with stock equipment if there are aftermarket performance parts available, meaning you will have to spend even more for the Hi-Po stuff. All I did to my car was a few bolt-ons, ground control suspension, a nice set of wheels and tires, and of course a stereo with in-dash monitor and DVD to round out the package. I'm pretty happy with the way it runs, looks, and sounds. Now, if you think $200 for a set of valve springs is a good deal (which I think it is), then a couple thousand more for a new cam, heads, lifters, porting, polishing, rods, and pistons must sound like a good deal too. You will have a pretty quick 4-banger, but is it worth the headache sometime down the road when you blow up the motor and have to go through the process again?