Er first of all why is this in the Honda section? Hola? Is it you Jk
Hey dude I have the same car as you do(manual), and let me recommend that you do NOT do anything with it. The car is like a piece of plastic on wheels, as said before the 1.3L engine is the most underpowered thing you will find(it's not a light car also) and unless you do a complete engine swap(why would you want to do that?) you're not going to get anywhere modifying it. And keep in mind people may be reluctant to buy it if you try to resell an N16 with a different engine. The only reason I had to get one is because I'm not in SL for more than a few months a year, and also because we managed to get it at a discount from the agents just before the taxes came in(they didn't have 1.6 at the time).
Oh and Pls don't be fooled by what the dealers tell you(they told me the same thing, and I knew it wasn't true, but at the time I had no choice). Use it as a point A-B car, and nothing more(turn the AC off while driving btw ) If you really want to do performance modifications, as stated before just sell it and get something better, there should be plenty of people willing to buy an N16. I've driven other Sunnys and this is the 2nd most underpowered model I've driven. As for you 100 in 8 seconds, I think that's a bit of a joke though I haven't really timed it myself. Touched 150 on it and didn't want to go any further at the risk of having the wheels fall off/car go out of control. Handling is crap, try taking a corner on a rainy day and then do the same in a better car, you'll surely notice the difference. One thing you will learn in this car though, is a few techniques for driving underpowered cars on SL roads, which might hold in good stead for the day you get a good car
Just sell the thing kid, and use that money on a better car+mods. That's what i'll be doing one day.