I have a 2015 IS250 and I’m looking to make some more power. Now before everyone tells me to sell it and buy a 350, that’s not an option. I’m just looking to do a few small things that will give me a bit more in the mid range. I plan on buying and exhaust and a new air intake, however I don’t know how much that will help. I know that engine is choked out horribly by its exhaust but I don’t know how much I’ll gain from a new exhaust. I just recently installed a limited slip diff from an FRS and the acceleration and handling has improved greatly. Just looking for a few more things. I only want to spend around $2,000. Let me know any suggestions.

 

2014 is250, I've got the Fsport intake filter/tube combo that @specONE pieced together in his build thread. You can get any high flow intake filter Tom's, K&N, or Lexus. I live in California so OEM was the only option for hassle free smog tests.
People have reported that cold air intakes actually result in performance loss due to heat, and that the OEM airbox design is pretty much peak efficiency.
I have an Invidia Q300H axleback, love it. Topped it off with a tune from RR-Racing. That made the throttle more responsive, and the car definitely feels better post tune. The intake and exhaust made the car feel better, but the tune makes the difference in my opinion.

Outside of lighter wheels and better tires, that's pretty much it for us if I'm not mistaken. I also have the Figs front LCA bushings to prevent the tire wear problem, outside the tune, this is probably my favorite upgrade. Steering is leaps and bounds better- you do get a bit more NVH though, but well worth it IMO.

I'm thinking of actually getting an LSD in there someday, how's it on the highway and on gas?

 

The LSD is amazing. It handles great and the acceleration and throttle response is way better than the oem Lexus diff. The Frs diff has a 4.10 ratio which is why I opted for that instead of the Lexus 3.90 gear ratio. I only lost around 2-3 mph on my top speed. Definitely worth it. I picked up a used one for $400 with 5,000 less miles than my car has. I haven’t taken any long trips just yet (I live in a small town, not much highway) but I haven’t noticed a decrease in gas mileage. Admittedly I have been on the gas more to “test” the diff so the only cause of decreased mpg is my heavy foot. I will be taking a trip this Friday and can let you know how it goes. Before I was getting 30 mpg.

I was looking into the Tsudo SP2 Catback exhaust for my car. It sounds good. But the only part I’m skeptical about is there’s no dyno to prove any improvement.

When it comes to the tune, RR-Racing has caught my eye. However it mentions that you might need to get a flash from Lexus to make the tune compatible. It also says some people already have this flash from Lexus. Do you know of any way to check if my car would need to be flashed? I don’t want to risk having to send it back because my nearest Lexus dealer is around a 7 hour drive. Plus it’s another $215 to get the flash.

Do you recommend getting the air intake? Or is it just not worth the money

 

I'll definitely keep an eye out for an FRS diff then. Lmk how the mileage is on that roadtrip!

I had the same question for them regarding the ECU flash and even asked the dealer to check if there were updates prior to asking RR-Racing (There wasn't anything). Turns out it was something for the earlier IS's, I believe yours should be fine since it's a year newer than mine, but send RR an email just to check.

Without real dyno results, I couldn't tell you. But the FSport intake tube is smoother, so it's theoretically better lol.
The same goes for the exhaust- I feel like they both gave me a little bit, but it's all butt dyno. Both the filter and exhaust gave me better sound though, a low-end rumble that turns into a nice scream at the higher RPMs.

You could probably get away with just a high-flow filter, but I love the look in the engine bay.
If you're not in a hurry, just pick up a filter, and wait for someone to sell their intake tube on here, someone got lucky with specONEs. He's local to me and I could've grabbed it if I had been more patient, but I found someone on eBay with used OEM clamps they'd only tried for fitment so I just pulled the trigger on a new tube and airbox lid.

 

What is a good price for the intake? I found everything for $360 including a filter. Thank you for the insight on the tune, I will send them an email.

 

No problem! and $360 seems like a good price, I looked on ebay and I paid $300 for the tube, clamps, and lid. 60 extra for the filter is fair, looks like 71 for the filter by itself.

 

Just got back from my trip, looks like any loss was only up to 1 mpg if any loss. Still was making 30 the whole trip, other than passing a few cars.

 

‘14 AWD 250 here. I like the car to remain quiet, so I’m not interested in an exhaust mod, what about a tune?

are there any plug-n-play tunes I can load, specifically to the factory Sport Mode?

 

Are you referring to one of those chip tunes?
RR-racings is an ecu reflash, pretty easy to do.
I don't have any experience with the other kind as the claims are rather outlandish usually.