FIFTY
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GranSport exhaust backbox upgrade
In January 2018 I was sent an link by a fellow former which was for an eBay listing selling a pair of used GS valved backboxes they were thinking about buying them and gutting the internals for their own GS however they ended going down the larini route.
The boxes looked a little tired guessing that is why they did not sell, I knew they are made from stainless so with a bit of determination they would clean up nicely. I used a wire wheel on a cordless drill to brush polish the corrosion off and road grime (e.g. tar) then went over it with a wool pad on the drill with autosol
Upon installation the valves are open and I found the car to be extremely loud with quite obnoxious drone around 2000rpm... Which is fine as long as if it is tame enough to live with when the valves are closed
Video clip from the halfway point of installing the boxes. It is not difficult but very fiddly. A ratchet spanner will save a lot of time installing the boxes onto the old mounts
I installed a vacuum line from the reservoir in the wheel arch to the back boxes following the brake lines. One thing to note is that the kit does not allow for anywhere near enough vacuum pipe so I had to order 4 meters more off Amazon
With the vacuum lines hooked up to the boxes the valves close and I take it out for a road test - the drone has gone thankfully - if it was not I was about to put the old boxes back on.
I then installed a remote valve control kit which uses an EGR valve that is installed along the vacuum line to control the boxes. I tucked the egr behind a heatsheild with it wrapped and sealed in a bag so it is not exposed
I can now switch between loud exhaust and even louder exhaust at the press of a button plus the GS tips look and sound great
One thing I need do address is that the control box is not on a switched circuit. There are no switched circuits in the fusebox located in the boot. It is a very slow drain but I generally eithrr disconnect the box or keep the car on a battery tender. The plan is to take the seats and carpet out so I can run a switched power feed from the fuse box in the passenger footwell (which is the same in the GS)
In January 2018 I was sent an link by a fellow former which was for an eBay listing selling a pair of used GS valved backboxes they were thinking about buying them and gutting the internals for their own GS however they ended going down the larini route.
The boxes looked a little tired guessing that is why they did not sell, I knew they are made from stainless so with a bit of determination they would clean up nicely. I used a wire wheel on a cordless drill to brush polish the corrosion off and road grime (e.g. tar) then went over it with a wool pad on the drill with autosol
Upon installation the valves are open and I found the car to be extremely loud with quite obnoxious drone around 2000rpm... Which is fine as long as if it is tame enough to live with when the valves are closed
Video clip from the halfway point of installing the boxes. It is not difficult but very fiddly. A ratchet spanner will save a lot of time installing the boxes onto the old mounts
I installed a vacuum line from the reservoir in the wheel arch to the back boxes following the brake lines. One thing to note is that the kit does not allow for anywhere near enough vacuum pipe so I had to order 4 meters more off Amazon
With the vacuum lines hooked up to the boxes the valves close and I take it out for a road test - the drone has gone thankfully - if it was not I was about to put the old boxes back on.
I then installed a remote valve control kit which uses an EGR valve that is installed along the vacuum line to control the boxes. I tucked the egr behind a heatsheild with it wrapped and sealed in a bag so it is not exposed
I can now switch between loud exhaust and even louder exhaust at the press of a button plus the GS tips look and sound great
One thing I need do address is that the control box is not on a switched circuit. There are no switched circuits in the fusebox located in the boot. It is a very slow drain but I generally eithrr disconnect the box or keep the car on a battery tender. The plan is to take the seats and carpet out so I can run a switched power feed from the fuse box in the passenger footwell (which is the same in the GS)
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