JAPSPEED GT86 – POWER & CONTROL

If you remember our previous updates to our GT86, we’d set the ball rolling by fitting a set of Eibach Sportline springs, a pair of Buddyclub rear lights and a set of XXR 527 wheels – some nice simple mods that plenty of people will be doing to their own GT86 or BRZ. By this stage we were pleased with the handling improvements we’d made, along with the subtle aesthetic tweaks that had left us with an all round more enjoyable car. However, it was time to start upping the power.

Replacing the stock exhaust on any car is always a popular route to take when first starting to modify it and we chose to follow this tried and tested route with our GT86.

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Introducing our Toyota GT86/Subaru BRZ Sports Cat Manifold, Sports Cat Downpipe and Cat Back Exhaust System. All three items are manufactured from high quality T304 stainless steel and feature TIG welded, CNC machined flanges for a perfect fit.

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The Sports Cat Manifold & Downpipe replace the OEM catalytic converters, offering improved flow characteristics while still remaining road legal and MOT friendly thanks to the built-in 200cell sports cats.

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The Cat Back System is 2.5″ in diameter and culminates with a pair of 4.5″ tailpipes that look suitably aggressive set against the rear bumper and under section.

We fitted the exhaust parts at John Clarkson Autos (a fairly local motorsport and dyno specialist) so we could accurately gauge how much of an effect the components would have on the overall power output and torque curve.

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First things first was to test the car in its standard form! We could barely hear the sound of the standard exhaust note over the sound of the rolling road but the results were a pair of runs at 201bhp and a final run at 203bhp.

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After a quick cool down we drove the ’86 onto the ramp to whip off the standard exhaust system running from the engine back. While removing the centre section and back box are fairly simple affairs, removing the skid plate and heat shield arrangement around the manifold took quite a bit of time.

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Despite this, replacing the exhaust system from the engine back is very simple and perfectly achievable by those who haven’t had any prior experience of modifying their car before.

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The tools required are no more extensive than a selection of 12, 13 and 14mm spanners and ratchets (with an extension) and a 22mm spanner. These are all you will need to remove and replace the manifold, downpipe, centre section and back box.

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The end result was an increase of peak power output to 207.5bhp at the top end of the rev range and a drastic improvement sound-wise.

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Improving a car’s breathing capabilities would not be complete without replacing the factory intake/air box – to do this we chose the AEM Toyota GT86/Subaru BRZ Induction kit.

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With the exhaust dyno runs complete we removed the standard air box setup from the car. This is an extremely simple process and only took our mechanic Ant a handful of minutes. Fitting the AEM kit is also a simple process (made easier by the included instructions!) and the entire removal and replacement process can be completed with just a flathead screwdriver, a Philips screwdriver, a 10mm ratchet, a 2.5mm allen key and a pair of pliers.

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No specialist knowledge is required and the fitting can easily be undertaken by yourself on your driveway, regardless of experience. For comparison, here is the standard air box having been removed from the car:

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With the Induction kit fitted we fired up the car and dyno and set to work on gaining some more figures.

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Once again the results were conclusive, with power now peaking at 214bhp and torque rising to 164lb/ft! Throttle response was also greatly improved and we enjoyed a much more entertaining drive back to Japspeed HQ now that we had a small power increase and the awesome induction noise and exhaust soundtrack to serenade us!

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Please note that our car had not been mapped to suit the modifications made it to it at this stage, so the next step was to treat the 86 to an ECUTek remap at AC Speedtech. With the remap complete we took the car back to John Clarkson Autos so we could get a true before and after dyno comparison.

Below is a comparison between the car in completely standard form (top graph) and the car with all Japspeed exhaust components, AEM Induction Kit and EcuTek remap fitted (bottom graph).

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Bearing in mind that, prior to the remap, the before and after dyno graphs followed a very similar shape, the ECUTek remap has made a world of difference. Gone is the flat spot between 3250 and 4750rpm – instead this flat spot is now located below 3250 rpm.

In the real world, the car’s drivability and fun factor have increased no end, with mid-range feel and responsiveness much-improved and helping to provide a much more enjoyable driving experience! Coupled with the induction roar from the AEM Induction Kit and the pops and bangs of our Japspeed exhaust setup, we’re now very happy with the car’s breathing setup.

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With the extra power beneath us we thought it best that we upgrade the braking while we were at it. Enter Tarox and their fantastic GT86/BRZ 326mm Front Big Brake Kit.

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Consisting of 326mm discs (available in Spiral Groove, Drilled & Grooved and Drilled & Straight Groove configurations), a pair of B32-6 six pot callipers (available in a wide array of colours) and Tarox’s own outstanding brake pads (available in Fast Road, Track and Race specifications) the kit is fully configurable for whatever usage your GT86/BRZ sees the most of, whether it be daily commuting, spirited weekend drives or all-out track use.

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The kit is also supplied with a pair of high quality braided lines, allowing you to replace the prone-to-perishing stock items and in turn improve braking feel.

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The larger discs and callipers also fit beneath the OEM wheels, allowing those with more standard looking cars to enjoy improved braking capabilities as well.

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They also fit perfectly beneath our XXR 527s, while looking absolutely awesome in the process.

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Overall we were absolutely chuffed with the end result – braking was massively improved and, combined with the increase in power and noise, the car was an absolute joy to throw around the country lanes, despite still remaining civilised when we wanted it to. The next step was to fit some of our new GT86 strut braces and improve the handling that little bit more – more of that in the next update.

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