Upgrading My 991.2 GT3 RS with a Manthey Roll Bar, Race Seat, and Harness!

In this upcoming article and video tutorial, I'll be installing a Manthey Roll Bar, a racing seat (either Recaro or Sabelt), and Schroth Racing harnesses in my 991.2 GT3 RS. This guide will walk you through the process, offering valuable tips for anyone looking to prep their car for the track!

 

How do you plan on turning off the airbag light? This is what has been holding me back from installing a racing seat.

 

How do you plan on turning off the airbag light? This is what has been holding me back from installing a racing seat.

Great question! I'll assume the dealership will clear the code. I'll confirm how they manage the airbag light and will follow-up in a few weeks.

 

Great question! I'll assume the dealership will clear the code. I'll confirm how they manage the airbag light and will follow-up in a few weeks.

From my research over the years, it seems that only Manthey themselves has the ability to code out the airbag light for 991s. A couple local shops have claimed this ability, however I have not seen any success stories.

 

Interesting. My roll bar and seat are being installed by Porsche so I'll assume they have the ability to code out the airbag light.

I plan to be at Porsche tomorrow and I'll ask the technician if he can provide addition info.

 

@DiscoWagon - talking to the service manager, sounds like they can code out the airbag light. I'll confirm with the technician once I do my final seat fitment.

 

Update – 15 Apr 2025:

• The Sabelt GT Pad seat won't fit in my 991.2 GT3 RS unless:
  • The door card and center console are removed.
• Ordered low-profile sliders to allow others to move the seat forward, but:
  • The sliders were too narrow for the OEM seat bolt locations.
  • Ended up needing to purchase the GMG adapter plate.
• Decided not to use the Sabelt GT Pad seat.
• Next steps:
  • Trying out the Sabelt Taurus and Recaro Profi SPG XL to see which fits me better.
    • Both should fit without removing the door card or center console.
  • Planning to create a custom harness to eliminate the airbag light if it can’t be coded out.
• Additional mods:
  • Modified the rear door cards to fit the Manthey roll bar.
  • Used a template for trimming – came out clean.
• Fitment notes:
  • Lost about 1 inch of rearward seat travel, so I'm sitting closer to the wheel than preferred.
  • As a bigger person, there's always a compromise with fitment.

 

Why did the rear door cards need to be trimmed for the roll bar? This is surprising as I always thought the MR bar was modeled after the OEM one.

 

Why did the rear door cards need to be trimmed for the roll bar? This is surprising as I always thought the MR bar was modeled after the OEM one.

That's what I thought as well. I actually asked the dealership to leave the rear door cards out, but it seems that message didn’t make it to the technician. Once I get the car back, I’ll post some pictures and share more detailed info on why the Manthey roll bar—supposedly based on the OEM Clubsport design—requires modifications to the door cards.

 

Update – 22 Apr 2025:

• Stopped at Discovery Parts located at Atlanta Motorsports Park (north of Atlanta, Georgia).
• Tried out a variety of seats in person.
• Chose the Sabelt Titan XL:
  • Felt the most comfortable and supportive for my build.
  • The Recaro Profi SPG XL was still too narrow in the back and shoulders.
  • Decided not to go with the Sabelt Taurus:
    • Don’t think I need the head restraints at this point.
    • Might revisit if I get into actual wheel-to-wheel racing.
• Porsche is handling the return of the Sabelt GT Pad and ordering the Titan XL.
  • Hoping Sabelt doesn’t give us any issues with the return—no restocking fees or surprise charges.
• I’m expecting to get the car back this week and will provide more insight into why the rear door cards needed to be modified for the Manthey roll bar.

 

Sabelt Seat Update:
Still sitting too high — even with adjustments, I don’t fit in the car with my helmet on. I’m continuing to explore possible solutions, but if I can’t make it work, I may have to consider selling the car. Definitely not the update I was hoping to share.

 

Have you looked at the Recaro P1300 GT? This is the seat for Cup Cars, what's special is that it has a specific seat rail where the sliders are on the sides instead of underneath. It should allow you to sit lower, but also there are different seat pads that can achieve an even lower seating position.

Another option is to bolt the seat directly to the floor, no sliders, as well as having the thinnest cushion possible.

 

Have you looked at the Recaro P1300 GT? This is the seat for Cup Cars, what's special is that it has a specific seat rail where the sliders are on the sides instead of underneath. It should allow you to sit lower, but also there are different seat pads that can achieve an even lower seating position.

Another option is to bolt the seat directly to the floor, no sliders, as well as having the thinnest cushion possible.

Thanks for the input! I'm actually heading back to Porsche tomorrow to re-test the seat. The current setup has the slider installed, and we’re planning to remove it to see if that gives me the clearance I need.

If that doesn't solve it, the Recaro P1300 GT is definitely next on my list. I know it fits in Cup Cars, but those have the door cards and center console removed — which is exactly why I had to move on from the Sabelt Pad GT seat. It fit fine in the Cup Car at the dealership, but not in my car with the interior still intact.

Either way, I’ll give the P1300 GT or something similar a shot before I throw in the towel. Appreciate the suggestion!

 

@DiscoWagon

Quick update on my project: I’ve asked Porsche to reinstall my factory seats while retaining the Manthey roll cage. Once I get the car back, the first thing I’ll try is removing the seat cushion bottoms from my Lightweight Buckets (LWBs) to see if that improves headroom.

If that helps with clearance, the next step will be developing a custom seat cushion setup for track use—something that offers better leg support along with added comfort for my lower back and buttocks.

I’ll also be taking a close look at the OEM LWB seat sliders. My goal is to either:
a) Design a fixed-position mounting solution that lowers the OEM LWD seat, or
b) Ideally, engineer a new system that lowers the seat while still allowing forward/backward adjustment.

The car returns from the dealership on June 2, 2025, and that’s when I’ll begin the engineering work in earnest.

 

Update – June 2, 2025
WOW! Removing the seat cushion from the Lightweight Buckets gave me plenty of headroom with my helmet on—an expensive lesson learned.

Next step: I need to develop a low-profile seat cushion that still offers solid leg support and improved comfort for my lower back and buttocks, while maintaining this newfound head clearance.

I’ll also continue exploring ways to lower the OEM LWB seat. That said, the electronic modules mounted underneath are very close to the floor—so relocation may be necessary if I go that route.

Engineering work begins now. More updates soon!

 

I've already done this While I probably have a different body frame (5'10" 165#), I always felt that the LWB did not sit low enough. I have been running custom P1 Designs inserts for the past few years and had the driver butt cushion made 1" thinner so I could sit lower. It made a noticeable difference and I use this cushion 100% of the time. P1 is great to work with, I would suggest reaching out to them for a solution!

 

Yep, I’m 6'3", 230 lbs—so headroom and seat ergonomics are a real challenge.

I spoke with P1 Designs yesterday, but I’m also planning to experiment on my own. My goal is to design and 3D print a custom seat cushion using a TPU cellular solid structure, similar to Porsche’s 3D-printed seat inserts—or even the lattice-style designs found in high-performance 3D-printed footwear.

This approach should give me the flexibility to fine-tune both support and comfort exactly where I need it. That said, my priorities are clear: first, finish the aero kit; then tackle lowering the LWB seat(s); and finally, dial in the custom seat cushion.