LS1 Modification Guide
As for any modifications, you should always start with the basics. You wouldn't want to try to run 5 miles with out training and/or breathing through a straw. -Correct?
First things first: Tackle the Exhaust system, cat back first, then Headers of your choice and Y pipe or true duals of your shoice. On LS1's, an airbox lid, filter and Ported and Polished throttle body are very easy, basic mods and should be done first. After you assess the breathing area, you can take on some minor suspension upgrades. Lower control arms, Subframe connectors and tansmission mounts are some of the first modifications that are the best bang for the buck.
FREE MODS:
Here's a couple sites containing full color photos about the freemods.
http://www.gmhightechperformance.com/tech/0311htp_ls1_fbody_10_free_modifications/index.html http://www.installuniversity.com/install_university/index.htm http://www.ls1howto.com
There are basically 5 free mods, all worth about 10 RWHP.
MAF Screen
You CAN remove the MAF screen by gently poking it out from the intake side to the filter side. If you damage any of the three sensing units in the center of the MAF, you will have serious drivability problems and in turn will need a replacement.
This subject has been one of debate. There is no actual proven power to be had here. The screen is used to evenly distribute the incoming air across the surface of the sensing element in the MAF. When you remove the screen, tuning it now can be troublesome. (LS1 Edited) Plus, you can run the risk of sucking in forgotten tools/ parts (hose clamps) that have been mistakenly left on your air filter during mod install...
The stock MAF sensor is also good up to a considerable HP level, so a 'high performance' replacement is not exactly necessary. Unless you are running some impressive flow #'s.
TB Bypass Mod
http://www.gmhightechperformance.com/tech/0311htp_projls1/index.html http://www.installuniversity.com/install_university/index.htm http://www.ls1howto.com
EGR Mod -Non LS6 intake
If you manually open the throttle, look inside. Where the EGR tube enters the manifold, in back of the throttle body, there will be a portion of the EGR tube protruding into the path of the incoming air. That needs to be chopped. Begin by removing the 10mm bolt that holds the EGR tube into the manifold. (from the top) Be sure to grab the O-ring seal, don't let it get loose in the intake. Pull the EGR tube up and chop the tube below the hat mount ridge. You can use a die-grinder or a dremel, what ever gets the job done. DON'T CUT THE MOUNT! There will be no way to remount the EGR tube if you do, and you can have a serious vacuum leak!
Once cut, remove the burs and shavings w/ a file or what ever works. Re-install and snug the mounting bolt back. It doesn't have to be insanely tight!
Drill Mod -For Master cyl clutch line.
The slave is buried under the power brake booster. You'll have to snake your hand and arm underneath to get it out (have patience, it CAN be done). Once you get it out, take a roll pin punch and remove the roll pin that retains the braided line to the master. The disconnect the fluid reservoir from the unit. Drain, but do not clean with water! Brake fluid absorbs moisture. You can use brakeclean if you want, but it could stain the plastic.
-DRILL MOD- -THE ENTIRE MASTER, RESERVOIR AND LINES MUST BE REMOVED TO PERFORM THIS MOD-
Wrap the master end of the line in an old hose piece to gently hold the master end of the braided line in the vice (looks like a brake bleeder valve. sorry no pic) If you insert the drill bit into the line with your hand you can feel an obstruction in the line. That's what will be drilled out. Use a 7/64" drill bit. The website, www.InstallUniversity.com, says to use an 1/8" drill bit, but I felt it was too big. Gently drill out the obstruction, lifting the drill frequently to remove shavings. Keep the line and drill bit as straight as possible as to not drill through the side of the braided line!
Voi La! You're done. I bled the line about a dozen times to be sure I removed all the metal shavings. Now bolt everything back up.
