Considering going the full Manthey Racing with your GT4? You should
By John Howell / Saturday, 7 May 2022 / Loading comments
I’ve driven the Porsche Cayman GT4 on track. That was at the fabulous Knockhill circuit. And the GT4 matched the verdurous, rolling beauty of the backdrop with its performance: it went round all day, lapping up the laps as it was born to do. It is, after all, a product of the motorsport department at Weissach, and motorsporty cars are what they excel at. Now we have the even more hardcore track car, the GT4 RS, which Matt Bird drove recently. If you’ve seen his video, you’ll know his voice went all squeaky. That wasn’t a helium leak; the GT4 RS apparently does that to you. Because it’s that good.
Let’s be honest, though – it’s also unattainable, at least for the vast majority of us. In theory you can buy a new standard 718 GT4, although if that too proves to be like alchemy in practice, you can absolutely pick one up second hand: for around £100,000, simply by clicking on the PH classifieds right now. And then if you find you would like it more finely honed for the track in the manner of the elusive RS, there are other things you could do. Like having a chat with RPM Technik.
This is the RPM Tecknik 718 GT4 MR, which adds Manthey Racing upgrades for, to quote the blurb, ‘extra spice’. It’s claimed to be ‘more engaging’ on the road and ‘scintillating’ on a circuit. Well, we can’t tell you whether the latter stands up to scrutiny, because we haven’t been on track with it, but we have driven RPM’s demo car on the road. Before getting stuck into its dynamic delights, though, time for a quick rundown of what you get for your money – and the sums involved.
RPM’s MR menu is a la carte, and begins with a spicy £12,750 stater (all prices are plus VAT). This kit includes Manthey coilover springs that drop the ride height by an ‘I mean business’ amount, and add dampers with passive adjustment for rebound and compression (the standard switchable damper button remains but becomes redundant, with phantom-limb resistors fitted to stop the ECU thinking something’s been amputated). The suspension hardware also includes new, solid uniball top mounts front and rear, and the inner bushes on the rear lower track-rod arms are rose jointed and shimmed to offer higher camber angles.
The pads are racing spec, the brake hoses braided, and there are a few aero tweaks: modified intakes, underbody air deflectors and an MR rear wing complete with Gurney flap. For £18,700, you get all that plus a set of lightweight forged BBS wheels. The tyre sizes are standard GT4, though, and the car we drove was fitted with Michelin Pilot Sport Cup 2s.
So, there’s your baseline MR car. And obviously once you’ve spent the money you can then spend hours playing about on the set-up side. Or, take the settings that Darren Anderson, RPM Technik’s commercial director (and owner of a very tricked-up 996 track-day special), says that he and Tim Harvey, RPM’s chassis consultant, feel make a good compromise. One that works on the road, in that it’s useable and makes the car more engaging, while on the track it should have you creating mid-corner consternation in the minds of GT3 owners. Of course, you’re free to choose something less aggressive or even more time-attack, should you wish.
On top of the chassis fiddling, you can go more fundamental, too. RPM offers a shorter final drive ratio with a new crown wheel and pinion. The intention here is to address the age-old issue of the GT4’s overly long gearing, which some feel blights the car. That upgrade costs £5,265, or £6,300 if you choose option two. Naturally, the shorter final drive makes the GT4 MR sing more on motorways, so option two has the tranquilising effect of a taller sixth gear. The demo car has the full Autobahn-spec overdrive sixth, but there’s a UK version coming that’s not quite so leggy.
On top of the new ratio, option two also comes with a lightened flywheel that does away with the dual-mass affair fitted at the factory. Naturally, there’s an exhaust upgrade: this stands you in at £3,000 and replaces everything aft of the petrol particulate filters, which were added when the 981 GT4 became the 718 GT4. The new exhaust retains the switchability of the standard system with a choice of modes.
There’s also a full brake rework for £10,350 supplied by Surface Transforms. This package bags you carbon fibre reinforced ceramic discs – 410mm diameter discs at the front with six-piston calipers, and 400mm and four pistons at the rear. Finally, as you can see, there are some ‘out there’ styling upgrades, too, although you don’t have to have these if you’d prefer to remain low-key – well, as low-key as you can be while running around in a GT4. And if your car didn’t spring from the factory with the Clubsport package, fear not. RPM will supply and install an MR roll cage, floor-mounted harnesses and a pair of original 918 carbon-backed seats to replicate it.
Give the starter a whir and kick the 4.0-litre flat-six into life and two things strike you immediately. Firstly, it’s louder and appreciably filthier-sounding from outside – even in the quieter mode. This is good. From inside though you can barely tell the difference; to my ears it’s no more boomy or raucous than the standard GT4. But it is lumpier. And before that observation is misconstrued as a criticism, it ain’t. Not at all. There are cars that should be quiet and serine, and cars that should feel raw. To me, a GT product ought to be among the latter, which is why I love that the MR makes you feel like you’re wearing its flat-six like a backpack at idle. The vibrations percolate through the stiff carbon seats as part of the racing theatre. In case you’re wondering, the added churn comes from the lighter flywheel, which has less mass to damp out the chunter.
When I initially popped the exhaust valve open, I didn’t like the boom it introduces. But that was ambling around; another listen while scything up the rev range proved a lot better. Past 3,000rpm, on a hard-pressed throttle, any boom has vapourised. Your left with a crisper, richer call. Now, this might not match the induction-roar heaven of the GT4 RS – and the GT4 MR doesn’t reach its heady, high-revving delights, either – but when it’s spinning up to its 8,000rpm limiter it’s not exactly lacking character, that’s for sure. Nor pace. The GT4 MR isn’t more powerful, but it is more urgent; noticeably so, thanks to the lower gearing. And because there’s less mass in the engine, every blip of the throttle comes with a burst of revs that make heel-and-toe shifts lightening quick.
Which brings me onto the brakes. Now, I’d say, and with some confidence, that Porsche is among the best at setting up a pedal box for heel and toeing. It’s all about the height of the brake relative to the throttle, of course: the more even they are the better. In the MR there’s more of a disparity, and having to twist my ankle to get the blips bang on was a let down. It’s nothing to do with the pedal box, which hasn’t been changed. It’s because the brake pedal is now so solid – with the ST running gear and braided pipework – that there isn’t the initial compression you get with the regular GT4, which puts the appropriate pedals on the same plane.
Well, not when you’re stopping relatively gently, as I was to begin with. It turns out I’m not the only one who’s pointed this out, because there’s an adjustable throttle pedal coming (yes, I know all throttle pedals are adjustable, but their mountings aren’t) to solve the issue. Although, as I found out later, when you’re really stamping on the brakes, which, by the way are massively strong on the retardation front, the issue goes away. And remember, this is more of a track day car, so chances are you’ll be stamping on the brakes a lot. If you’re not, you’re not trying hard enough.
There are other quirks, too. Like, for example, the chatter from the geartrain when the engine’s labouring below 3,000rpm. This sounds a bit like a knackered-out input shaft bearing, but nothing’s on the way out here. Once again, the cause is the reduced damping effect of the flyweight flywheel, and, once again, as far as I’m concerned, it adds to stripped-bare motorsport spirit. It’s not annoying, which I’m not sure I can say is true of the new sixth gear.
I’d suggest strongly going for the UK halfway house variant rather than the taller fitted to this demo. That might be fine at Autobahn speeds, but at 70mph you go from fifth, when the engine’s pulling around 4,000rpm, to sixth, and the tacho needle sinks to a lowly 2,000rpm – just beyond the engine’s comfort zone. Other than that, I like the shorter final drive. As I said, it makes the car seem racier but also less thwarted by its lofty second gear. The standard GT4 will exceed 80mph when you ring its neck in second. So if you want to avoid a hug from the long arm of the law, you can only rev it out fully in first. Well, you can safely max out the GT4 MR in second because it tops out at 70mph, and even on country roads it makes the experience more engaging.
Which brings us onto the steering. Like the brake pedal, the changes here had me fretting at first. Connecting your consciousness to a car’s front wheels is another given in virtually any modern Porsche, but in the MR there’s some vagueness either side of dead centre. Obviously, this was a concern. I imagined it was going to make the car less precise on tight lanes, where you need to be deadly accurate between any kerbs that crop up to avoid taking lumps out of those lovely, forged rims. Yet, twenty minutes into my drive, there was no damage to the wheels. I found myself placing the car easily, even with the little extra pull you get over cambers – more than I remember feeling in the regular GT4.
It’s still a slight trade-off, mind, but you appreciate what for come the first long, fast sweeper. Oh my, the bite from the front tyres and the reassurance you get when the front end is loaded-up is a thrill. Even if you’re name’s Tom, Dick or Ham-fisted Harry, I don’t think you could miss the MR’s added panache. And in case you’re thinking it’s all locked down for a track, it’s not. If anything, it’s more agile in the slower-speed stuff. Barrel into a roundabout with a little lift midway through and the rear starts to swing. It stays delightfully cockeyed with some power on the exit, but it’s not loose, as such. It’s still predictable, just more spirited and helps the car turn.
The suspension set-up is just as impressive. It’s tauter than the standard GT4, although not in a bad way. Again, this being a proper, purposeful sports car it’s meant to feel firm. And there’s a key difference between firm and fidgety, and firm yet supple, like this is. Sure, the MR punches hard over potholes and sunken manhole covers, but it doesn’t decimate your spine and deals with the aftershocks swiftly. Like any good set up, the smaller imperfections are filtered away so you’re not left in a state of constant agitation. As with the steering, there’s payback, too: the dampers are like a dog with a bone. They just won’t let go of the body, so the GT4 MR is able to deal with tremendous vertical challenges at full pelt while appearing to mutter under its breath “pah, is that all ya got?” And when you think the car isn’t running the road-biased settings it has access to, that’s pretty damn impressive.
That’s the overriding thought, as it happens. I think ‘impressive’ best describes the GT4 MR. Sure, there are things that I’d change, like that Empire State Building sixth gear, and I’m not hugely drawn to those lairy decals, either. But everything else gets a big thumbs up, mainly because of the accompanying big smile the MR induces. Any initial scepticism – the fear that the GT4 MR might be a GT4 made worse, for the road at least – peeled away under use like a visor tear off.
In fact, the more time I spent exploring and playing and delving into its reserves, the more I came away thinking the opposite is true. Obviously I can’t confirm whether the GT4 MR is a giant killer on track, but crikey, I would be very surprised if it isn’t. I can tell you, categorically, that it’s a car you should drive to the circuit, not trailer. The GT4 is still wonderful – the MR configuration doesn’t change that. But, as Porsche proved with its GT4 RS, you can always go one better. The difference is, when you have a chat with RPM Technik, which I really think you should, you’re guaranteed to get a ‘yes, of course we can help’ instead of a polite ‘maybe next time, sir.’
Specification | RPM Technik Porsche 718 Cayman GT4 MR
Engine: 3,995cc, flat-six, naturally aspirated
Transmission: six-speed manual, rear-wheel drive
Power (hp): 420 @ 7,600rpm
Torque (lb ft): 310 @ 5,000-6,800rpm
0-62mph: 4.4 secs (standard car)
Top speed: 189mph (standard car)
Weight: 1,420kg (DIN)
Price: £46,020 inc. VAT (plus donor car)
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