Looking to see what my best route would be to gain some affordable reliable towing power. Wondering before I start cause I know each build is gonna require different intakes and exhausts

 

Or buy a new vehicle that suits your towing needs much better.

 

Now why would I do that? I love my Fit, just wish it had a tiny bit more power

 

To get any sort of useful advice, you need to specify what you're trying to tow and what your issues are in regards to towing with your Fit. Fuel economy? Ability to maintain a certain speed going up a hill? More payload? What?

With a small vehicle like a Fit, it doesn't take a very large payload before NWCH's advice is the obvious and correct answer.

Just for giggles, lets pretend you could somehow double the horsepower and torque of your Fit. I would argue that your (safe) towing capability wouldn't increase. If you tow with a Fit you're already fighting against basic physics because of low vehicle weight (and GVWR), limited rear axle strength, front wheel drive platform, limited and narrow wheelbase, limited cooling capability, and limited braking capability.

I grew up on a farm pulling heavy payloads with proper towing vehicles. If I really needed to I would be okay pulling maybe 1000 lbs (trailer + payload) behind my Fit. If I had to do it regularly I would add a transmission cooler and better brakes or (probably) consider a more appropriate vehicle. Adding more power to my Fit might let me pull 1000 lbs more easily or while getting better fuel economy, but it wouldn't mean that I would suddenly think that I could tow 2000 lbs.