Cylinder 4 coolant mod: people think they need to cool cylinder 4 because that's the one that knocks first. But that's also the only cylinder with a knock sensor. Which is why you think it knocked first. So now you cool it and then one of the other three starts knocking. Only now you won't know about it in time because the knock sensor on cylinder 4 isn't picking it up. And so there go your pistons.

Hi Duncan, Great video. Thanks! Ramping up the production quality 👌

Only guilty of the short shifter, my 96 impreza had the 1993-1995 style shifter and i had changed the linkage to the 96.5+ but didn't have an OEM to put back into it due to the difference in linkage ends for the older shifter

Would be interesting to hear your take on Catch Cans/ Air Oil Separators. Also aftermarket air intakes (cone filter things), heard the stock one is good enough for most applications!

Another enjoyable and very interesting video Dunc, keep them coming!

Love it! So truethful.

Another gem of information...You have a new subscriber

Another Great video Duncan, as a new Subaru sti owner it’s brilliant watching your videos and couldn’t have been more of a gent mapping my widetrack sti last week at Surrey rolling road. Straight forward and sound advice.

Excellent video as always thank goodness I only have 1 on the list the turbo timer thank you for keeping my car running can't wait to have the clutch done see you soon thank you

The cylinder 4 thing, you probably haven't dealt with the justification for it because, judging by your accent you probably haven't dealt with too many 2.5l turbo engines. I'm with you, I also feel like they're unnecessary. The idea is allegedly that cyl 4 runs hot, which causes detonation and causes the cyl 4 ringland to break. Now it's true that cyl 4 does run hot, but IMO the product of that is not detonation, just regular old ring butting. The EJ255 as found in USDM Legacy GT, Outback XT, Forester XT, WRX, etc has a teeeeeny tiny .009" ring gap. No wonder the pistons break. The cooling mod doesn't fix it, it just means some other ring will maybe butt first. If you ask me the 2.5l displacement across the board was a huge mistake, they should have never made an EJ larger than 2.2, or if they did they should have done it through stroke.

Ha ha. Enjoyed your super calm rant. Made total sense. My JDM Legacy has run sweet since you tweaked it for UK fuel. Would be most interested in the pro arguments for No.4 cylinder cooling mod.

All good advice mate, with your experience in high performance subis, you definitely know ya stuff! Cheers mate, for the brutal honesty too, love it 🤙

That’s answered some of my questions! Thanks

Great Call on the Coil Packs...

Very interesting share your opinion on everything you mentioned

#9 I agree but I will find out as I have egt going in on a factory header and will see what temps are like prior to doing the mod pending I feel there enough of a temp difference to do it

Great video, I believe the cylinder 4 cooling mod is mostly a thing for us USDM folk that have unequal length headers from the factory.

I love your common sense approach.  A lot of what you are saying goes for all cars.  Cheap parts a never a good idea if you are keeping your car.

That Cobb shifter news is worrying..

Please do a part 2.. would like to see catch cans as a topic.

Another great, informative video! Thank you! If we are playing "Scooby mod bingo", the only mod I have on my FSTI that is on the list is the Cyl4 cooling mod and I was skeptical about it from the start, so I used a heat gun to check before and after, and it did bring the temp on cyl4 down a bit, but we are talking 3-5deg C (taken on the surface of the head). The overall temp of the coolant was also reduced a little bit (around 5c). Those tests were only done at idle when the car was up to temp and the results are negligible so my conclusion: Does it need the mod? No. Does it hurt to have it? probably not. If I get another Scooby, will I do the mod again? I doubt it. I am a bit concerned that the only knock sensor is on cyl4, so if (big if!) I have reduced the probability in knock on 4, have I reduced the overall knock protection??