Tools:
Jack
Piece of wood that spans the hump in the rear of the subframe. Say a 4x4 about 2 foot long
jack stands (2)
1" extension
3" extension
18-24" extension (for downpipe bolts)
15mm wrench (pivothead ratcheting preferred)
15mm socket (Deep SnapOn ball pivot preferred)
13mm socket (Deep SnapOn ball pivot preferred)
10mm deep socket
5.5mm socket
18mm socket
Ratchets 1/4", 3/8" at minimum (pivot head locking with long handle preferred)
Plug socket
O2 socket
Rubber mallet
Procedure:
Remove plug wires from plugs and leave them on the coils, laying on the motor.
Remove plugs (pulling dogbones and using passengerside to move/hold motor is easiest)
Remove driverside crossbrace and intake (3 x 13mm)
Remove crossover to front manifold bolts. Loosening equally is your best chance to get them off w/o snapping. (2 x 13mm)
Remove crossover to rear manifold. Loosening equally is your best chance to get them off w/o snapping. (4 x 13mm, 2 nuts, 2 bolts)
Remove nut holding oil dipstick to front head (1 x 13mm) Wiggle/pull to Remove dipstick. (Pulling actual stick out keeps top piece from breaking)
Remove nuts holding heat shield over front exhaust manifold (2 x 13mm)
Remove engine lift bracket (2 x 13mm)
Remove nuts/bolts holding front manifold to head (6 x 13mm)
Remove the two end studs from the front head (2 x 5.5mm) Gasket should come off at this point.
Jack and support car at the drip edges. (These are the thicker area of metal in front of the door that the owners manual tells you to use as jacking points.)
Go under car and remove the bolts from downpipe to catback (2 x 15mm)
Remove rubber donuts holding rear of downpipe (large screwdriver)
Unhook O2 connector to rear sensor.
Remove two studs/nuts holding the downpipe to rear manifold (2 x 13mm, possibly 15mm on some 97's) Downpipe should now be out of the way.
Unbolt EGR to rear manifold (1 x 10mm, newer years it's a 13mm)
Remove O2 sensor from rear manifold (7/8" O2 socket)
Remove nuts holding engine cover bracket to rear exhaust studs (2 x 13mm)
Remove rear engine lift bracket (2 x 13mm)
Remove rear exhaust manifold bolts/nuts (6 x 13mm) Note: one is next to the bolt from the EGR. Tough to see.
Remove studs from head (2 x 5.5mm)
Position jack with 4x4 under the rear of the subframe, in a manner that it paralells the radiator and will support both sides of the subframe. Remove the two rear subframe bolts (2 x 18mm)
Lower the rear of the subframe 3 inches.
Wiggle rear exhaust out through the bottom.
Wipe down rear exhaust gasket and have prepared.
Wiggle new rear header into place, put exhaust gasket in place and use studs to start the ends and hold the manifold with nuts started on the bolts. Do not tighten
Raise subframe and reinstall bolts (2 x 18mm)
From above tighten the studs back into head (2 x 5.5mm)
Begin tightening nuts and start all other bolts. As you start these bolts watch the EGR tube and line it up in the hole on the rear header.
Bolt the EGR tube to rear header (1 x 10mm or 13mm)
Tighten the rear header to the rear head
Put rear crossover clamp on and position in a way to make it easy to tighten the clamp.
Put crossover in place
Put front crossover clamp on and position in a way to make it easy to tighten the clamp.
Start front header into the crossover, position gasket and get one or both of the studs into head started and put nuts on them to hold them.
Tighten the studs into head (2 x 5.5mm)
Start to tighten the nuts on those studs and lightly tap the crossover with a rubber mallet to facilitate/vibrate it over the front header.
Get the remainder of the front bolts started.
Tighten the front bolts slowly while continually tapping the crossover with rubber mallet. (6 x 13mm)
Once they are all tightned down the crossover/front header should be all set.
Tighten the front and rear crossover clamps.
Reinstall spark plugs and wires being careful not to have a plug wire touching the headers.
Reinstall intake
Reinstall crossbrace over intake
Connect O2 extension harness and route so it will not touch headers or plug wires.
Go underneath and clean catback exhaust flange surface for the new gasket.
Put racepipe or catted pipe in place on the downpips and clamp.
Slide new catback gasket in place and bolt together (2 x 15mm)
Put O2's in place and connect them.
Lower car to ground and fire it up.
Originally Posted by bluegtp91
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