I think this is just one case I've seen on here, but an IS300 AWD with the tune recently his car going into limp mode and he had to flash back to stock. Also, a few of us with the tune, myself included, are having issues with the tune only shifting up with paddle shifters at WOT. RR Racing has mentioned a different tune that might fix this, but I haven't tried it yet. Personally, I would not waste my money on a 350, you are getting 10whp and a slightly higher redline. That is way too much money for such little gains. Also, I'm not entirely sure that anyone has ever done a pre and post dyno showing what the actual benefits of the tune are for people with full catback, headers, etc. I think it is somewhat misleading to say that the tune is what is giving the car 44 hp with header/exhaust and 25 hp with catback since the stock ecu will probably readjust afterward installing anyway and there will be some gains regardless of a tune. You'll notice on RR Racing's dynos that they usually show stock, then stock plus tune, and stock plus tune plus exhaust, never a stock plus exhaust only. On prior cars, I've always done a baseline, a dyno pull with headers/exhaust, and then custom tune, and I know with my VQ35, it was not the tune that netted the entire gains, it just helped to maximize the mods.

 

Do you notice it pulling harder in the lower rpms? Ie. You start off in manual mode M1, then floor the gas pedal, is there a significant difference before and after in the above scenario?

 

I would describe the lower RPM difference as noticeable, but not significant if that makes any sense. I happened to swap back to the stock IS300 tune for a few days last week(from running the full RR racing tune for ~2 months coming previously running a stock 350 tune for a while, on a AWD 300). Around town and immediately off the line if felt pretty similar. I really noticed the difference above ~4K RPM though. It's a big difference flooring it on the highway (stock 300 vs full RR racing tune) and with the tune the car feel surprisingly quick when you floor it from ~20MPH or ~45-55MPH. Compared to the stock 350 tune the extra RPM feels like it really helps when you floor it anywhere from ~20 or 45-55RPM. Once the engine is in the power band it feels like your able to keep it there for longer. I have not gotten to time the full RR racing tune like I have the stock 350 tune yet. Unfortunately I still have not gotten around to it.

 

Just to clarify, you own an IS300 (2016) and the "stock 350" tune is just the RR Racing tune without the 7200 rpm redline?

 

Maybe? By "stock 350 tune', it's a tune that is apparently identical to a stock AWD IS350. I don't really have a way of directly comparing the tune to a OEM stock 350 to be sure it's identical, But it sure feels just like any of the 350 AWDs I drove (I really wanted a 350 but in the months of looking around me no really nice ones came up, so it was the choice between a super clean AWD 300 FS or a hooptie 350AWDFS.) When I switch to the full 7200RPM RR-Racing tune I can feel the difference in throttle response sensitivity and the shifts feel a little harder and not quite as smooth all both even at slow speeds, so I'm assuming it's identical or close to a stock 350 AWD tune.

 

what are the benefits of a RCF Bushings? I have a 16’ IS300 AWD with Ark exhaust

 

Better front tire wear and a a little bit more of a stiffer steering feel. Easily the best mod I've done next to my exhaust. The stock bushings from the IS are so soft that during turns and braking, the toe angles for the front wheels dynamically move in whichever direction the IS moves into which explains the premature, lateral tire wear you'd never expect. My stock Turanzas were chewed up at the front but the rear tires still had plenty of tread left. It also doesn't matter how you drive because that's how the IS was designed. The RCF bushings mitigates that issue and this is a highly recommended mod but if you have a little more to spend and want even more stiffer steering feedback, check out the USRS bushings from RR racing.

 

I was looking to get the tuner too for my 300 FSport 2016 and still thinking about it as we do not have any chance of checking any calibration like you could have with the JB4 on a phone or so .. also the fact that doing a good tune would put the car on a DYNO to make sure all parameter are pointed to the right specs. To be true, i haven't found any darn place in Quebec that i could bring the car to have properly tuned and dealers .... loll no way they want to get into that !!! Kind of stupid from them a bit :P
I'm pretty sure that this 3.5 V6 could put-out a lot more torque and WHP with a good setup
As for the bushing like silbecar said .... IT'S a must if you like to drive with a better handling ... changed mine too and way better cornering and stability .... OEM used to make wheel rub in inner fender (no lowering kit) at higher speed cornering lol