GR Yaris Best Value mods for performance gains

Woody

New member
Dec 31, 2021
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Hi all

There are many options for increasing power for the GR now .

Please list your favourite upgrade that's made noticeable power increases. I'm looking for the best bhp for £.

Hopefully this will help me with future performance additions. ( Future budget around 2-3k , so no big engine builds😂)

Thanks all
 

Bronson

Totally Hooked
Dec 16, 2021
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Isle of Man
If you just want to increase the power then depending on where you use the car and it’s jurisdiction, a decat and GPF delete (£600) should free up 20 HP.

A decat would require a remap, a GPF delete won’t. Remaps available from £4-600 (but for me the jury is still out on the long term effects of this) or you can use a tuning box with their associated risks.

Keeping things on the legal side an air intake duct may help a little bit, as with upgrading the turbo inlet - a good job to do at the same time (£300).

Intercooler (£700+), HJS downpipe if you don’t/can’t decat (£1500); both legal and not overly complicated.

The main caveat is that BHP increases are seemingly quite difficult to accurately gauge with this platform. Yes the car will feel like it’s pulling more, but what are you actually getting?

For me the car responds better to lightening and suspension tweaking. Also uprating the pads, lines and brake fluid (easily done for less than £500) and your confidence on the brakes will make up for any ‘shortfalls’ in power.
 

Woody

New member
Dec 31, 2021
29
5
3
Thanks for your response, I'm only using the car for b roads and no track days. If I remap with Litchfield Ecutek or colins software do I require kelford value springs ?

Is the hjs down pipe with gpf and Fujitsibo exhaust any good ( I realise I can remove the gpf but then I'm not insured if I crash ) 🫣

Looks like the forge turbo inlet and air inlet are a option , with standard air box. I

Thanks
 

Michael Knight

Totally Hooked
Dec 7, 2021
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www.grcf.fi
Thanks for your response, I'm only using the car for b roads and no track days. If I remap with Litchfield Ecutek or colins software do I require kelford value springs ?

Is the hjs down pipe with gpf and Fujitsibo exhaust any good ( I realise I can remove the gpf but then I'm not insured if I crash ) 🫣

Looks like the forge turbo inlet and air inlet are a option , with standard air box. I

Thanks
Yes for higher boost map valve springs is the way to go
 

GR.KEV

Dedicated member
Jan 8, 2023
216
147
43
Worcestershire
Hi all

There are many options for increasing power for the GR now .

Please list your favourite upgrade that's made noticeable power increases. I'm looking for the best bhp for £.

Hopefully this will help me with future performance additions. ( Future budget around 2-3k , so no big engine builds😂)

Thanks all
Collins re-map all the way, plus exhaust and intake 🚗💨
 

Woody

New member
Dec 31, 2021
29
5
3
If I go for the HJS Downpipe, what make is best , I see milltek and hjs make them , as you can tell I'm a little confused 🤔.
 

GRunt

Obsessed member
Feb 17, 2022
491
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Northern Germany
Afaik hjs make the cat and milltek just put their name on it. Probably easier to buy the milltek in the uk.
Yes, the milltek is just a HJS with rebrand.

Fitting isn't that easy because it's very tight around the downpipe. Some workshops remove the drive shaft, other don't. But it's sure a fiddle job. It takes about 2 hours on first try, but many workshops are getting faster on consecutive jobs. Than it's about 1 hour.
 
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yuri1312

Devoted member
Dec 7, 2021
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what needs to be removed for valve spring swap? just thinking options here.
if you don't want to drop the engine down from the bay (which will take more effort, but give you more room to work), essentially it needs to be stripped down as such:

IMG-20220913-WA0114.jpg


IMG-20220913-WA0112.jpg


springs can be changed without removing the head by pumping compressed air into the cylinder to keep the valves from dropping.

then "just" reinstall everything back - implies making sure timing is properly dialed in, etc etc. also some gaskets should be replaced to avoid leaks - at least high pressure pump, valve cover, and vacuum pump.

One important thing, if not dropping the engine, be very careful when refitting back components (especially in tight areas, such as when refitting the timing covers, as they're relatively brittle if not handled properly). take your time to put things back together correctly, and follow the fricken service manuals on how to do it properly. don't rush things or you'll be in a world of trouble.
 
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