Wow. ECU's on modern cars are ridiculously controlling. So you would not recommend header and s-pipe?
In the case I decide to dam the torpedos and go for header and s-pipe, Do you believe if I threw in a high flow cat, or resonator it would sacrifice the power gained from said bolt ons?
What kind of handling improvements would I notice if I put on the trd shocks? What other aftermarket shocks are on the market for the tC?
Thanks enginfineer. You have helped my comprehension a lot.

 

This myth needs to curl up and die. Not singling anyone out because this line is still being regurgitated on many threads, but how the s-pipe became such a magical piece of empty pipe without a single dyno or 1/4-mile time to prove it is hard to comprehend. While it is the most restrictive PIPE in the exhaust, and absolutely should be replaced on a turbo car, spending $150-200 on s-pipe to gain maybe the equivalent of a dyno error is unnecessary for an NA tC. After putting on header and axleback, you have maxed out your exhaust gains and you will get almost nothing in performance return for any $$ spent on s-pipe or midpipe.

To the OP, get a header to finish out your breathing mods. Then as you brought up yourself, get engine management - Camcon and E-manage are popular choices - to maximize those mods. There's someone on SL now who is about to hit 180whp with essentially bolt-ons and Camcon on his manual. Your auto won't reach those numbers but you will still see nice gains for your money if you have a good tuner in your area.

The downside of tuning is dyno time $$ which can be expensive - in my area the going rate is about $125/hour for the tuner, and about $85/hour for dyno time to tune it yourself. If you know how to tune or if you can swing free dyno time you can save some money. Just make sure as engifineer said not to tune too lean or you will knock and damage your engine.

 

In the case I do go for a header which one has shown the most promise in power gains along the full spectrum?
and...
To eliminate rasp gained with the introduction of a aftermarket header would the addition of a high flow cat eliminate said rasp without sacrificing the power gained? Or Would a Magnaflow Resonator work better?

 

Header design is actually very complicated, and they can only be built to maximize power over a certain RPM range. For midrange power (around 3-4,000 RPM) the best independent dyno results have been with the 4-1 designs:

https://www.scionlife.com/forums/viewtopic.php?t=82724

For high-end (above 4K RPM) the 4-2-1 designs show the best gains, these would be the Weapon-R and similar headers.

Prices vary too, just search around and pick the one you like best. If you're getting EMS I would get the cheapest dyno-proven header you can find and save your $$ for the dyno because you're going to see more gains from a good tune than from any bolt-on alone.

Yes, rasp is a big issue with putting a header on this car. If you plan on keeping your Megan exhaust I would sell the midpipe portion and re-use the stock midpipe (if you still have it). This would allow you to use the stock cat - which seems to flow pretty well for NA, and have an exhaust shop remove the stock resonator and put on the longest aftermarket resonator (magnaflow is good) that will fit. If you're keeping the Megan axleback you will need all the help you can get to quiet rasp. The cat + resonator should do it.

 

I have researched further into the greddy emanage ultimate, and I have seen supplement harnesses sold alongside of them, what exactly are these harnesses, what do they do?

 

they allow you to plug and play without having to splice wiring in your car to get them to work. they allow you to just plug directly into your car without cutting anything.