One of the first, must-do mods to the Ralliart: Upgrade the Intercooler system
Now that you know how the basics of how the system works, you can see how important good cooling is. If you want the most pressurized air, you want it as cold as possible. As air is pressurized, molecules will collide and will cause more heat and want to expand (losing pressure again). The intercooler keeps air temperatures down to help prevent this.
When the intercooler can't keep up with cooling the passing air, it is known as "heatsoak" and the intercooler isn't accomplishing it's job. The OEM Ralliart Intercooler is pathetically small and gets easily heatsoaked. The more and more your car runs, the higher and higher your air temperature (and in turn, your boost pressure) will increase. Obviously this will cause a loss in power.
Luckily, a used OEM Evo X intercooler setup is a direct fit and a very cost effective upgrade AND can easily be done in your garage. It is not very technically challenging. I recommend buying at least a FMIC AND LICP.
"What about piping? I heard the upper hose NEEDS to be upgraded to a hard-pipe, but the LICP is fine?"
Remember how the intercooler system works. The Upper Intercooler Pipe (the black hose from the factory) is BEFORE the intercooler. The only problem is that this hose expands under boost pressure. Remember, this air is still going into the intercooler to be cooled - so the UICP is not a major factor in total power output - but you lose throttle response: as you floor it, some of the boost pressure is lost as it expands the upper piping hose - but it STILL goes into the intercooler afterwards.
After the intercooler does it's job, then the pressurized air is on it's way to the engine for use. This is the MOST important component. There is nothing left but this pipe before this pressurized air is used - so you do not want to worsen this air in any way possible. The stock RA LICP, which is made of plastic, has a small diameter (which causes heat as particles collide) and an unusual bend (again, another place for collision and heat generation). The Evo X LICP is a finely crafted piece - made from aluminum to hold the air, a bigger diameter, and very smooth curves for a clean flow straight to the engine. Almost nothing interrupts the air as it is fed to the engine with this pipe - which is what you want.
This is the biggest misconception that RA owners seem to have. Most think that the UICP is the biggest restriction and that the LICP is fine. The expanding OEM UICP hose just lose you throttle response, but still accomplishes it's job of sending the air to the intercooler.
The OEM LICP, with so many bends, ruins work that the intercooler accomplished. With so much restriction in flow and bends causing collision and heat generation, you're ruining the work of the intercooler just before the air enters your engine for use.
But with how cheaply you can pickup a whole Evo X set (UICP + FMIC + LICP), I recommend you replace all pieces at the same time. This also avoids any fitment issues - just complete replacement with 100% fitment.
What about aftermarket?
For UICPs: This is a good choice for customization. Any hard pipe will prevent expansion and improve lost throttle response that the OEM hose has. Since there are so many available and are relatively low cost, many opt for an aftermarket UICP when upgrading to an Evo X FMIC. When upgrading to any Evo X FMIC (either OEM or aftermarket), you will need an Evo X specific UICP
FMICs: An upgraded FMIC core is always nice, but within reason. Remember that the purpose of the intercooler is to keep temperatures down. The intercooler doesn't really generate power as much as it prevents power loss (from heatsoak). You should pair the appropriate intercooler size with the turbo you plan to run. An Evo X FMIC is more than enough for the small size RA turbo. You're not going to gain much power off a huge 4" intercooler when it's still being fed a small amount of air by the stock RA turbo.
LICPs: There really isn't much to improve on from the OEM Evo X piece. It's aluminum with good flowing bends. There's not much to improve on as far as material used or shape, so the Evo X LICP is actually as good as most aftermarket pieces out there - making it a GREAT budget upgrade.
Fitment:
- An Evo X FMIC (stock or aftermarket) is taller than the RA's, so an UICP is needed to match lengths
- The outlet of the Evo X FMIC is larger than the sizing of the OEM RA LICP, so a reducer coupler will be needed to fit properly
- Because of such low cost of used Evo X UICP and LICP, it's much easier just to buy a whole set and avoid any fitment issues - and gain the most out of the whole setup
- Because the intercooler will be cooling whatever turbo or whatever boost pressure you are tuned for, upgrading this first gives plenty of forward growth for whatever your further plans are