Experience of using V4 tunes from OFT in Britain
 

Been running V4 tunes on my GT86, because headers are so expensive in Britain, I took the route of replacing the cat in the OEM header. Running what would be E10 fuel in the USA, Mishimoto sound generator delete on induction pipe, panel air filter.

• Visually, it's pretty much impossible to spot the cat has been replaced by pipe in header. With OEM heat-shields around header and skid plate, it looks standard.
• Noise levels tootling about are unchanged, when you are revving out in 3rd, there's an increase in roar from the exhaust outlets, but it's by no mean obnoxious, since the standard exhaust is kept from the over-pipe.

Performance changes -

• Motorway driving, much improved. I never liked that 5th gear at 60mph was smack in the middle of the torque dip, so overtaking or going up a long incline required you to change down. No more! I found accelerating in 5th from 60 to 80 is now acceptable to keep up with traffic, although not with the push of a turbo car, of course
  
• Acceleration from rolling start. Much improved, coming off a roundabout in 2nd, then a pull on the straight up to 100[1] in 6th was smooth all the way, no 'step' as you spun past 4,000rpm. It's not a rocket ship, but a gain of 15whp and smoothing out torque dip seems quite plausible. Zipping up to 100 is now easy as pie.
  
• Point and squirt around town - keeping in 3rd, feels quicker in the 15 to 40 mph range to move into traffic gaps

I'd say this achieved my goal of 80% of the gains of new EL header and bespoke ECUtek tune at much less than 80% of the cost, plus the car still looks and sounds stock and no CELs

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Nice job. Did you change to stage 2 tune?

Stage 2+ as catless header

What fuel octane are you running with?

99 RON with 5% to 10% Ethanol,

nice. was gonna do this on 17+ headers. did u do the welding with the headers on the car or off the car? my only concern doing it off the car is that fitment would not be 100%

Without rescaling your MAF table?
I used V4.03 OTS ROM for my MY18 BRZ and I could say although they improve the car they don't match our EUDM models, at least with our poor quality fuel.

The cat replacement was done off the car, actually I bought it already done so I have the unmodded header to swap back if I sell the car. I was told it took some work to shape the pipe to fit after the cat was removed, keeping the flange to the overpipe in correct position.

>Without rescaling your MAF table?<

I didn't. The AFR stays about 14 and I've not seen any issues with long term fuel trims.

I only use the highest RON fuel available in the UK.

You are lucky or your version OTS tunes match better your car, in every case 14:1 is quite lean at high rpms/load, are you sure you haven't knock?

knock indicator not shown any cause for worry on the OFT real-time display.

I'll post some data sets on that thread

you can t have 14 afr on high load.. if you really have it, you should worry a lot

Yea 14:1 is bit to lean for my liking at WOT. Work with some individual tuners who post here to get your maf re-scaled. Your car will thank you..

Wait is this 14:1 at steady state cruise or WOT.

It's amazing how often people jump to conclusions. On any stock/OFT tune I think it would require something completely off to run 14:1 at WOT.