XT performance mods

[Seabass]

Sticky Please.

I'm writing this as a reference for other xt owners on here. It seems like every week the same questions are popping up. Let me know if I am missing anything. Instead of re-inventing the wheel, this will be mostly basic info followed by links to more detailed threads.


Mod Stages:

Read Here for the stage definitions from the lgt.com sticky. Below are the simplified ones that I normally see used.

Stg 1: Just a tune on an otherwise stock setup. Usually around 15-16psi. Appx power: 220whp/220wtq. Stock is about 190whp/190wtq.

Stg 2: Aftermarket downpipe, catless up pipe (05-06), and tune. Appx power: 230-250whp/ 250-280wtq depends on tune and whether you run aggressive boost and an upgraded intercooler.

Stg 3: Aftermarket turbo with stock internals. Basic supporting mods include catless up pipe, downpipe, aftermarket intercooler, injectors, and fuel pump. The exception to the fueling upgrades is the 16g turbo (or similar sized turbo) which can be run on stock fueling with boost tapered at high rpm.

Stg 4: Aftermarket turbo on build engine with all of the previous mentioned supporting mods.

Tuning options:

Read the stickies HERE!

Opensource: Using free software to flash a tune to the ecu. These tunes are opensource in that you can read the tune and alter it if you wish. The most popular option is infamous tuning and performance.

05-06 models can use a cheap chinese vag-com cable from ebay or the more expensive tactrix cable.

07+ models need the tactrix to be able to flash a rom to the ecu.

Setting up a vag-com cable!

Tuning/logging software: Romraider, Learning View, ECUFLASH, FreeSSM. More on these tools later in this write up.

*Note on tactrix cables: The newer tactrix 2.0 cables are not compatible with freessm software. Tactrix cables support logging to microsd card as well as connecting to a laptop.

Accessport:

Considerably more expensive than opensource. Comes with OTS (off the shelf) maps. Gives you several more tuning options and is much more convenient in that you don't need a laptop to flash or log and can flash between different maps very quickly.

Self Tuning:

Do you have too much time on your hands? Then read all of the stickies in the LGT.com tuning section that I've linked to. Then read all of the tuning how to's on romraider.com. Then think about whether you want to take responsibility for possibly blowing up your engine. If you're ok with that, then there are base maps HERE! If you mess up, it's your own fault. The tools required are the same as mentioned in the opensource tuning section.

Other FAQ's:

Intake:

You don't need to do anything to your intake until you get a MUCH bigger turbo. Getting an aftermarket intake or even drop in filter will require a tune. The maf scaling will be off and can lean out your afr if you don't scale it properly. So unless you like detonation, stay with stock or get a proper tune for an intake.

Exhaust:

05-06 has a cat in the up pipe. Replace with an aftermarket up pipe or sti up pipe.

Do not get an aftermarket downpipe without a tune! It is dangerous as the ecu is unable to compensate enough to make such a dramatic change safe.

The stock cat-back is not a restriction until you get a bigger turbo. Even then, there are a lot of people running 20g turbos on the stock catback.

Intercooler:

The stock intercooler is known to separate at the passenger side end tank. This usually happens at stage 2 power levels, but can happen even on a stage 1 tune (ask me how I know). Here's a Bulletproof mod to reinforce the tabs on the intercooler. Or you can just upgrade to an aftermarket intercooler.

Software tools:

For links, go to the opensource tuning part of this post.

Romraider is a tool for rom editing and logging. It's a good tool to have even on a stock setup to learn about how the ecu is controlling everything. It's also a good tool for making sure your car is in good working order.

Ecuflash reads and flashes roms to the ecu. It is also a rom editing tool.

FreeSSM is an opensource version of SSMIII that dealerships use for diagnostics. It can be used as a CEL reader as well as for ecu/tcu resets and several "tests" that you would normally have to go to a dealership for.

Learning view will give you a snapshot of areas the ecu has learned to pull timing because of knock. It will also show you the fuel trims. It's useful for diagnosing a boost leak or vacuum leak. It is also a CEL code reader.

Banjo filter:

This one you're going to have to search for. Basically, there is a mesh filter in a banjo bolt in the turbo oil supply. It can clog and starve the turbo of oil if you are lax with oil changes. If you remove it, you may be opening up the possibility of oil contamination problems destroying the turbo's bearings. Figure out whether you want to check the PITA filter occasionally or whether you want to pull it out.

Or you can just replace the oil line with one from infamous performance that has a serviceable filter in it. They also have an option for an oil line that relocates the oil supply line so it does not share oil with the AVCS system.
Banjo filter removal.



There's plenty more info, so let's get it out there. Any other suggestions?

[Seabass]

Transmissions:

5eat:

The 5eat can take huge amounts of power while in gear, but it burns up the clutch packs during heavy throttle shifts with over stage 1 power. Your current options are to either let off of the throttle during shifts or if you have an 05-07 xt, you can do a valve body mod. Having taken a ride in a stage 2 lgt with a transgo vb mod, I can tell you that the difference is impressive. You can chirp the tires from 1st to 2nd at wot. There are currently no options for the 08+ 5eat, but it's being worked on. If you drive aggressively and wot shift a lot with stg 2+ power, you will eventually burn up your clutches. Especially from the 3-4 and 4-5 shifts, which are slower than the others and usually with higher boost.

HERE'S the vb mod thread. ClimberD has done an insane amount of work figuring out the valve body and is currently trying to figure out the 08+ vb. You can either send him your vb and he'll mod it and ship it back insanely fast, or you can go on a wait list for him to send you out a modded vb and you send back the one that you uninstall for no down time.

Then there's the Transgo kit. Here's the walkthrough if you're feeling a bit nuts. ClimberD wrote up a DIY thread for the transgo shift kit for the nissan/jatco 5eat which is extremely close to our 5eat. The pictures are intimidating, but those who have done it say it is not that difficult with the excellent instructions, just time consuming. The kit can be purchased HERE from summit racing. The transmission can remain on the car to install this.

If you like to launch your car, you will eventually tear up the needle bearings in the center diff. Those will then eat up the rest of the center diff. The solution is solid bushings. Here's the thread.You'll need to email climberD about these to purchase them. The transmission can remain on the car to install these.

It's a good idea to add an atf cooler if you are modding. You'll get a lot more heat from the torque converter even with stage 1 power levels. If you live somewhere that's extremely cold during the winter, get a cooler with a thermostat. There are already threads here for this, so just search for it.

5mt:

I've done absolutely no research on the 5mt, so I'll let someone else chime in on this one. LALGT? How much can the stock clutch take? How much can the trans take before you should take out a second mortgage and do a 6spd swap?

Read the transmission stickies at lgt.com.

[AWDFTW]

Stickied per OP request.

[Seabass]

Thanks!

[LosAngelesLGT]

EDIT: SPOT SAVED FOR 5MT TRANS INFORMATION. (No personal experience with 6mt)

Brief 5MT trans info: OEM trans and clutch good for stage2 but expect the OEM clutch to wear sooner than it would otherwise. My 5mt has held up to many many relatively gentle dragstrip passes and 425wtq. Its hardly the glass tranny the early WRX trans were known to be but I would expect something in the driveline to break with numerous drop clutch drag launches at more than double the OEM wheel torque and a cluch more than able to hold the power. Personal info on COMP and Exedy as well as reference material for a variety of clutches will follow as I get a chance.

In the meantime anyone with specific questions about getting more power is welcome to PM me or post up.

OG POST: Thanks Seabass. Great idea. The misinformation spread regularly on this forum by some regulars makes me want to flame people. Now I can just link this thread since some folks seem scared of LegacyGT.com.

[Seabass]

Done.

Any other things you'd like to add?

[WagesOfZin]

fantastic! my head has been swimming as of late with searches and bouncing from thread to thread and forum to forum as i try to wrap my mind around all of this while simultaneously trying to remember what i read where and how it was relevant to something else i read in another thread, on another forum, etc.

subscribed.

[aftCG]

You rock Seabass. Glad this was finally done.

Your numbers correspond closely with what I learned when I started (taken from dyno charts on LGT):

Stock 191whp/190wtq
Stage 1 225whp/228wtq
Stage 2 234whp/251wtq
Stage 3 245whp/275wtq

Had my car in the mud last weekend. It's just as insane in snow and mud as it is on dry pavement.

[Seabass]

Awesome. Now we need to get the transgo kits installed in our cars! Mine was 180whp/180wtq stock and 220whp/220wtq at stg 1 according to my logs. Now I'm a bit lower due to a leaky intercooler.

[Rester5350]

Wow this is AWESOME, thank you guys!!!