991.2 GT3RS Splitter Installation



  • Wheels;
  • Front wheel liners;
  • Front Lower under panel;
  • Front bumper;
  • Radiator Ducts;
  • Lower crash bar;
  • Horns.

2. REMOVE 2 lower M8 bolts on bottom of the bumper mounting flanges.

3. INSTALL Left and Right Bumper mounts with new supplied M8x35mm bolts. The mounts are complete with Tension rods installed, however not yet adjusted.

4. REMOVE OEM brackets from Horns.

5. INSTALL supplied new Brackets onto horns.

6. INSTALL back into place. The Horn should be facing into the hole in the back center radiator support and the bow in the bracket should be facing AWAY from the tension rod for clearance.

7. REMOVE both LOWER bottom radiator mounting bracket M8 bolts.

8. INSTALL Lower mounts with new M8x30 Socket head bolts. Before tightening the mounts completely, Slide or push the brackets towards the middle of the car.

9. INSTALL both 5/16 threaded studs into the mounting brackets.

10. Measure center to center on the studs. The dimension from center of each stud should be 844mm or ALMOST 33 1/4”. Adjust the mounts if needed to obtain desired measurement. Be sure the studs are bottomed out, then install the thin jam nut on the back of the mount.

11. REMOVE both small plastic mounting brackets on the outer edge of the radiator brackets. Use a pic or small screw driver and push the pins out, and then push the bracket out. Clean the surfaces on the top and under side of debris.

12. INSTALL new side side radiator mounting brackets with new supplied M5 bolts. Snug the bolts up and then back them off about 1/2 turn. Leave these loose until the splitter is fitted. This allows for adjustment later on.

13. BEFORE INSTALLING MAIN MOUNTING BRACKETS. Clean the surface of the front body of the car where the mounting brackets will install. Remove debris and dirt to allow the brackets to sit against the body

14. INSTALL mounting brackets first onto the body over the studs, and then the crash bar over top of the brackets.

Use supplied M8 large washers on top of the bracket and then install original M8 Nuts for the crash bar. This is easier with 2 people, however you can install only one bracket and crash bar loosely on one side, then retain with a nut on top stud, then install the other bracket under the crash bar on the other side and retain with another nut. Then install the 6 M8 washers and the original nuts.

15. INSTALL support brackets onto Main mounting brackets.

16. When installing these brackets you will need to slip the tension rod Clevis Rod end into the top of the bracket just to loosely locate it. Then on the bottom of the bracket it will locate into several holes and nut inserts for several bolts.

Make sure the rod end is able to move freely. Install 6 M6x12mm bolts onto each bracket loosely, then install 4 M6x12 socket head bolts into the FORWARD FACING holes behind the nut inserts. These are used as there is no clearance for M6 Hex head bolts here.

Once all the bolts are threaded in, they can be torqued to 7-8lb ft. Repeat on the opposite side.

17. INSTALL Clevis pin into the Rod end and through the support bracket hole. INSTALL the R clip onto the pin. The clip should be on the BACK side of the bracket.

18. ADJUST the height of the bracket by turning the Turnbuckle to lengthen or shorten the tension rod.

19. INITIAL spec for the height is from the MIDDLE of the main mounting bracket front edge, measure to the TOP of the welded on bracket on the bumper support. This dimension should be 10.75-11.0” We recommend starting at 11”.

After the splitter is installed, you can move these as needed for perfect splitter fitment on the car as well as to the front lip. We have had 11.0 and 10.75” work on different cars.

DO NOT tighten the jam nuts until final splitter height has been set.


1. INSTALL 4 white plastic spacers onto the splitter using the 8 short M6 torx socket bolts. These only need to be snug. The bolts go into the 4 forward most holes and then the outer holes this way they do not hit the mounting brackets.

2. INSTALL the large outer rub blocks with the provided M5 screws.



Slide splitter onto the rear middle mounting studs. The splitter should slide on with ease and only minor force. Once slid on, use the M10 Flat head bolts to install splitter to main mounting brackets. Install all 4 bolts, however leave them 1-2 turns loose from fully tightened down.



1. With splitter loosely installed, use the M6x25 Flat head torx bolts, thread them through the splitter and rub blocks into the side rad mounting brackets. Thread them in but leave them 1-2 turns loose.

Do this for both sides.

2. Once both are installed, push the splitter rear ward and then tighten down the M10 Main splitter mounting bolts firmly.

3. Next tighten down the T30 head M6 flat head bolts on the back corners of the splitter into the mounting blocks. Snug these down. Next, tighten the M5 bolts that hold the mounting blocks into the radiator bracket.

4. Torque these to 5-6lb ft.

5. Remove all 6 splitter mounting bolts and remove splitter.

6. Re install splitter onto studs and then all 6 bolts again to verify fitment and location of all bolts.

7. Remove splitter.

8. Install radiator ducts.

9. Install bumper BUT DO NOT FULLY INSTALL.

10. Install upper retaining clips and side corner screws only.



1. Assemble lip with provided M5 bolts and nuts.

2. The bolts are a snug fit into the lip on purpose so they need a little force to install.

3. Start with the corner lip piece and work towards the center. Install each piece and snug the screws down.

It is ok to FULLY assemble the lip as one piece and install OR.

It is also ok to assemble each side, or LEFT and RIGHT halves and then install both halves onto the car and then bolt the sides together in the middle.

Both ways are acceptable.

4. Once assembled, install the lip like the OEM lip, it will press and clip into the bumper.

The corner lip piece will be snug to clip in, and then the lower tab will be screwed into the bumper.

5. Once the lip is fully fitted and installed, install the splitter blade again and snug the main 4 bolts down. Verify splitter fitment to the lip. If the splitter is too low, then measure the distance, and adjust the turnbuckles up or down as needed to move the splitter blade to match the lip.

6. Once adjustment and fitment is complete, the front bumper can be fully installed for the final time.

7. The Bumper lower corner will be attached to the main radiator mounting blocks with the M6x16 flange head bolt and M6 washer.

8.Install splitter blade.

9. The wheel liners will need to be slightly trimmed to clear the splitter.

Line them up and mark as needed and cut the plastic to clear the splitter as shown.

Install the liners and all trims once complete.

10. Install End Fences with 4 M5x20 socket head bolts. DO NOT overtighten. These should be snug not torqued down with an impact gun.

11. Install Vortex Generators with M5x12 socket flange head bolts.

12. Install front middle nose Rub blocks with 4 M5x25mm flat head bolts.

13. Reassemble front of the car.

14. Stand on front splitter nose and bounce on the splitter to test that it is installed correctly.

15. Record a video of this and post to Social Media and Tag @dundonmotorsports in the post.

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