|The more air moved through an engine, the more
power that can be produced. Generally one of the first modifications to
any car is to replace the usually restrictive OEM exhaust with an after
market 'cat-back' performance exhaust. Cat-back refers to replacing the
mufflers and the pre-silencer, so replacing the exhaust from the catalytic
convertors back. This mod can release up to 25rwhp depending on the exhaust
and other mods. This installation is of a BandB 2.5" system on a '93
TT. 3" system instructions are also included, but not illustrated.
1/2" drive Air impact wrench
4 metal exhaust gaskets (2.5" systems) PN 206092-1E810 (not verified
yet w/ Courtesy)
Pre Installation Note:
If installing a 3" version, read step 8 VERY carefully to avoid major headaches halfway through the installation.
1. Disconnect the negative terminal of the battery. Jack up the rear of the car. Put it either up on ramps or on jack stands. I prefer ramps, there's more elbow room over jack stands.
2. Get under the car and spray everything exhaust related from the catalytic convertors back with a penetrating lubricant. I recommend 'Blaster' brand. This includes nuts, bolts, rubber hangers, the bolts holding the rubber hangers, everything.
3. Remove the nuts on the muffler hanger (4 x 17 mm) using the impact wrench (1.). Swing the muffler back off the pre-silencer and bracket studs.
4. Use a pry bar to pop the muffler off of it's rubber hangers. Do the front one first and let the muffler hang down a bit to help pop the hangers out of the rear mounts (Orange Dots in 2. and 3. are on the pry bar for placement).
5. Remove the muffler from under the car and perform the same procedure on the other side.
6. Remove the safety bracket from under the front of the pre-silencer section of the exhaust (4 x 12 mm). Using the impact wrench, the extension, the U-joint and sockets in whatever combination works best, remove the nuts and bolts from the catalytic convertors holding the pre-silencer in place (4.). The U-joint will help the most with the nuts on the top part (5.). Slip the rear hangers off the pre-silencer, then remove it from the car. For BandB systems with the dual 4.5" oval tips, remove the rear tow hooks (4 x 14 mm), the tips won't fit in there with the hooks in the way.
For 3" systems skip to step 8.
7. Hang the new metal gaskets on the studs of the catalytic convertors. Put anti-seize compound on the studs and bolts. Figure out which end is up for the X/H pipe, it's difficult to flip it over once it's under the car (6.). Stab the X/H pipe onto the catalytic convertor studs. The gaskets will be hanging down, that's OK for now. Run the rear hanger studs through the rear flange on the X/H pipe to hang then entire piece in place. Use a finger to swing the metal gaskets up into place.
Skip to step 11.
8. With the larger O.D. on the 3", things get really tight around the studs. 'Cap' nuts are definitely needed. These are really thin walled nuts. The 17 mm OEMs have a lot of metal involved. The cap nuts will be 14mm, but still have the same I.D. A set of bolts with the same threads will be needed as well with 14mm heads. The 17 mms WILL NOT FIT! Before really getting into this, I suggest crawling under the rear of the car and popping off one of the nuts holding the muffler to the pre-silencer for a thread reference. Then got to Pep-Boys or the local import speed shop and get the right hardware. The kit would consist of: 6 nuts and 6 bolts total. 2 nuts and 2 bolts for the X/H pipe to catalytic convertor. 4 nuts and 4 bolts for the muffler to X/H-pipe. The most trick method would be having hex headed bolts, this solves a lot of the headache of the 3" system. I did this with mine when mating up 3" test pipes to the 3" X pipe on my BandB, SO much easier.
9.Put a small bead of Copper Seal on the catalytic convertor flange. Put anti-seize compound on the studs and bolts. Figure out which end is up for the X/H pipe, it's difficult to flip it over once it's under the car (6.). Stab the X/H pipe onto the catalytic convertor studs. Start the lower bolts first to hold the X/H pipe up, then start the nuts. Don't tighten them just yet. Once again, the 3" causes some clearance problems. The hangers that provide the connection between the muffler section and teh X/H-pipe won't fit. Remove the hangers (2 x 12mm) to get them out of the way.
10. Put a bead of Copper Seal on the loose flanges on the X/H-pipe. Do step 13, except use the extra set of cap nuts and bolts from step 8. Once everything is in place then tighten down the nuts and bolts to the catalytic convertors. The best speciallized method is to put a 14 mm 1/4" drive with built in U-joint (Snap-On) on the nut and slip a 12" 1/4" drive extension over the top of the X pipe to get to the top nuts. I had to beat up the aluminum plate above the pipes a little bit to make this work. Other variations on this theme will probably work to some degree. The box end of a wrench wouldn't work, because the wall of the box end is too thick, otherwise it would work the same as the 2.5" version. Unfortunately, a torque wrench doesn't do much good here, since everything's too tight to get it into motion. I just lean on the wrench hard to make sure everything is tight. Reinstall the safety bracket (4 x 12 mm) (7.).
Skip to step 14.
11. Using 3/8" drive U-joint, shallow socket and extension, start the bolts and nuts back in. (4 x 17 mm). The socket depth will run out eventually. The X pipe keeps me from using a deep socket with the U-joint, an H pipe will probably allow it. The angle of the top nuts is just enough to allow a 12th of a turn, then smallest increment on a 12 point box end wrench. Keep tightening everything with a wrench. Unfortunately, a torque wrench doesn't do much good here, since everything's too tight to get it into motion. I just lean on the wrench hard to make sure everything is tight. Reinstall the safety bracket (4 x 12 mm) (7.).
12. Install the metal gaskets on the studs. Put anti-seize compound on the hanger studs coming through the rear of the X/H pipe.
13. Figure out which end is up on one of the mufflers. Stab the two rear hangers first (8.). Stab the front hanger next (9.). Swing the exhaust and stab it on the X/H-pipe studs. Do the same for the other side. Run the nuts down close to tight (2 x 17 mm).
14. Get the Z back down on the ground off the stands or ramps.
15. Stand 20' behind the car crouched down and look at the muffler can/tip's angle ('before' 10.). There's a little free play in the studs up front that will allow some tweaking on the angle. Twist the pipes however necessary to make them level. I am able to get under the car with it on the ground well enough to tighten the nuts (and bolts on 3") with a socket wrench. If you're a little wider that I am, or the car is lowered, a U-joint and a long extension should get you through. I had to tweak the right exhaust tip on Allen's car to make things look square. On 3" systems, check to make sure the top of the pipe is not rubbing the bottom of the HICAS linkage. I stick a wrench inbetween the pipe & the linkage while tightening the rest to make certain the space is maintained.
16. Reconnect the negative terminal of the battery. The ECU has probably had enough time to reset during the installation. If there's no noticeable power gain, try leaving it disconnected overnight. The ECU goes through a 'learning' process after reset to adapt to changes made to the car.
Originally published 7-25-99
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