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Discussion Starter · #1 ·
I know this detail is already scattered around a few threads, bits and pieces here and there, but I thought this post might be useful for those considering the 'big picture' for upgrade planning/expectations or perhaps those considering the IS250 AWD as a new purchase for various reasons...

I have recently acquired a (new) '09 IS250 AWD. AWD was a requirement for me, for my family. Interior options aside it came with the F-Sport exhaust pre-installed, a freebie per the dealer, I did not complain. It is not truly a dual exhaust, nor does it add any noticable power, however it looks good and has a nice tone to it. If it was not already on the car I probably would not have bought it.

I had driven just about everything AWD I could get my hands on and liked the IS for the size, style, and fit - for me physically and my garage :) Even the gas mileage was not bad for the comparable vehicles I had driven. The only thing I did not like on the IS in general was the body roll. There was a noticable lack of rigidity and handling in every one I drove. The ride was not as upright as I had felt in other vehicles. Fortunately I had felt this before and believed this to be an easy fix.

- I drove it for a few days and then dropped in a K&N air filter. I noticed an instant ~1.5 MPG improvement, up to almost 27 from 25-ish doing 80/20 (hwy/city). This MPG increase came with a mild change in throttle response and no additional 'noise'. Granted the engine was (is, @ 3K) still breaking in, but removing the K&N filter and installing the paper stock filter again I saw the MPG drop back down. Confirmation that the drop in filter was sure to pay for itself soon enough. Anyone who has an ISx50 who does NOT want an intake mod should at least do the drop in as it will pay for itself many times over.

- I installed the sway bar kit (front and rear) along with the x-brace as planned. I had seen other posts where some installed only rear sway's on an AWD (???) I could not understand why someone would do the front without the rear, and include the middle (x-brace) for that matter. I negotiated a good price on the parts and combined labor at the dealer. The handling issues were resolved, not just around turns, but the little things like lane changes and even lower speed scenarios in parking lots are more precise. The overall ride is comparable to my former 7-series bimmer (after the suspension was completely rebuilt 'like new') and the skid pad 'simulation' felt a lot like a new M3 I recently drove. Please note I am NOT comparing POWER just HANDLING.

- I proceeded to leverage my recent activity with my dealership to move on the F-Sport intake. The install was practically free and the price was close to dealer cost (after sharing with them what some other Lexus dealerships would sell me the part for online with free shipping to their dealership for installation under warranty) so they met the cost and I went for it. I noticed an immediate increrase in throttle response throughout the RPM range at all speeds. This may not be a big HP gain, if any, but it IS a considerable difference that makes the car more responsive, seemingly "quicker" between gears. This is more important to me in a vehicle with less HP - I want to get to what is there with minimal delay, and that is exactly the result I got fromm the F-Sport intake. The sound was also more pronounced in the low end with a nice tone. The noise increase is minimal, if any, at highway speeds, with no impact to the audio, voice recognition, handsfree, etc... I could not be happier with that!

- In regards to MPG YMMV with the F-Sport intake vs drop-in (K&N) or similar I am as good if not a bit better than the K&N/stock combo numbers at highway speeds. However, I DID and you WILL likely see a DROP in efficiency on the backroads in trade for the throttle response, which can reduce MPG's to sub-20 if you put your foot on the floor and keep it there. That will probably get you a 'bonus' brake job a lot sooner than you need one, but that's just a symptom of a driver with that 'lead foot' diagnosis.

Note: At this point I would like to note that I believe the previous suspension work may contribute slightly to the overall efficiency of the vehicle, it rolls straighter with less tendency to lean due to the grade of the road. I noticed this in the rain as well, drove a few hundred miles over the weekend through some very wet conditions and the vehicle seemed more stable in those conditions than before the sways and brace, it's all relative I suppose.

I have built suspensions on many vehicles. Cars, trucks, old and new, big and small, and the IS sway/x-brace was one of the most effective and reasonably priced upgrades I can ever recall - the best bang for the buck and the first thing any IS (AWD, at least) owner should do.

In my opinion, there is no sense in lowering a car that's still going to roll on you through the turns, it may help some and look good, and you can add the bigger wheels to also help with the appearance [and reduce useful power in most cases, actually], but that's not me. My 1st hand opinion is do the sways/brace 1st and lower later if you feel the need. This will improve handling and you get to keep the ground clearance, which is probably desireable if you chose AWD. The way I see it lowering just increases the chance of getting stuck when you need AWD the most.

The intake debates are what they are... K&N drop-in, Joe-Z, *whatever* - If you add up the pieces and negotiate well with your delaership the difference is not that much and the result will be as advertised. I mentioned that previously with the drop-in comment (above). With the F-Sport intake I am getting as good if not better highway MPG (32.1 max with K&N vs. 32.6 max with F-Sport intake so far with tank averages about the same so far...) on a very specific HWY route if I baby it with no ECT adjustment, VDIM enabled, and no cruise control. I do find that PWR ECT does not impact highway MPG much as some posts have indicated, I ran around 27 MPG average a couple of trips with it on and just over 28 in standard mode using the same 80/20 (hwy/backroad) route in similar weather with cruise control. There are a good 15 or so hills on the route in my daily commute, so with PWR ECT the shifts are a bit more aggressive, RPMs hang a bit higher at times, which eats some additional fuel. That difference in MPG does seem to be related more to the PWR ECT and less to the intake for the route in question.

Although the the F-Sport mods may have only given me an additional 8-10 HP I will be able to enjoy the MUCH improved handling, SIGNIFICANTLY increased throttle response, and appreciate the use of PWR ECT without too much concern for dumping my fuel economy. I will also be able to go directly to the source with any issues I may encounter. That was part the idea of buying new in the first place, not grabbing one for sake of rebuild or excessive mods.

Now that the suspension is 'corrected' and the flow is sized for what is under the hood I'll think about some summer wheel/tire combos, but with no sense of urgency. That may wait until the end of this year when I put some good snow tires on the stock 17" wheels. I think the extra grip will be welcome with my current suspension setup, as will the winter tires in place of that crap the manufacturer puts on the car (my only other real issue with the car off the lot aside from the body roll).

As for the shocks and springs, I'll wait until the shocks are worn and then probably upgrade. I honestly don't ever see a need for springs on this vehicle considering the available power and distribution thereof. I am not a fan of lowering vehicles unless there is a very specific scientific reason and I see none in the case of the AWD IS250 (constructive comments with supporting data are welcome). My experience is although a lower center of gravity can be GOOD, I find it has more of an impact in terms of appearance, and mine looks just fine as it is! :approve:

In closing, if you like the look and feel of the IS250 AWD and can present yourself as a well informed owner at your local dealership I think you would be happy with the setup above. By doing your homework and negotiating it through the dealership the mods are resonably priced, the car is more stable, more fun to drive, and it is all covered by your warranty.

And FWIW the above upgrades won't keep us with the IS250's siblings equipped with bigger engines on a straight away. After all you can't compensate for a 100 HP, but add some twists and turns, maybe a side road and you might be surprised who winds up in whose rear view mirror - I know I was! :cool:

I hope this helps somebody!
 

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Discussion Starter · #3 ·
...I did - with Yokohama's AVID ENVigor's - sweeeeet!!!!!!!!!!!!
 
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