View Full Version : Babalouie’s Lexus ISF XForce Exhaust Review

28-08-17, 05:32 PM
Regarded as one of the mainstays in the Australian JDM scene, Kevin, or Babalouie, or just Babs, had purchased one of our XForce exhausts for his Lexus ISF! He’s well known for his informative, funny, and highly detailed build threads for each of his car. Read on to find out how he installed the exhaust, what he thinks of it, and of course a video of him blasting around the track. Just listen to that 5L V8 sing! Be warned, there’s a fairly long read ahead of you!

The Toyota IS500 got a bit of love on the weekend for...this! An X-Force dual exhaust, supplied at a very reasonable price by sparesbox.com.au.




First to be removed is the axleback section, and that starts with dousing all the rubber hangers with spray lubricant. They don't come out easy, as the "mushroom" on the end of the hangers is pretty big.


It was easier to remove the hangers from the bodyside as a result. These are the hangers next to the diff.


The hangers for the twin mufflers are much harder as you don't have access to spray the front with lube, and there isn't room to get a prybar in there.


Ever wondered why Lexus are usually pretty heavy? Well it's because they do things like make chunky muffler brackets that are held on by three massive M10 bolts. I'm not sure why they need to be so overbuilt, you could probably support the weight of the whole car from one of them.


Axleback section out...you have the space and time to prise out the rubber hangers from next to the diff.


The stock mufflers look massive and are heavy, but the choke point of the whole system is probably this squashed oval section that goes under the diff.


The transmission tunnel has two braces; one is easy to unbolt, but the other has bolts which are behind the plastic under tray.


Then you remove the two O2 sensors. The ISF actually has four; the other two are on the headers. For this, you'll need a Toyota/Lexus O2 sensor removal tool, which I bought off eBay for $80.


And with the O2 sensors out, the centre section can be removed from the car, by supporting the back on a jack, while you unbolt it from the headers. The X-Force is a dual system, with one 2.5in pipe per bank, that merge together in an X. The stock pipes actually start out as also 2.5ins, but they merge into a central resonator, then into that squashed oval bit, before finishing in 2.2in pipes to the mufflers.


Now, as to why you need the pipes to meet in an X...I think the Engine Masters boys do a much better job of explaining it than I could :)


So the X-Force should be less restrictive on pipe size, but the new exhaust is catless, so the secondary cats are eliminated. This should remove quite a lot of restriction.


The car itself still has two cats inside the headers though. And here you see that the headers don't use a conventional gasket; instead there's a crushable ring.


But the flange on the X-Force does not...I fitted a new oem crushring, and when you tighten it all up, the flanges don't actually meet when the ring is fully crushed. It doesn't leak, so I figure this is how it's meant to be.


Fitting up the new exhaust is much quicker then removing the old one. I'd say the whole job took three hours, and 70% of it was getting the old one off.


Refit the O2 sensors, after giving them a couple of twists anti-clockwise (so that the wires are straight when it's done up).

And we are done!


Babalouie’s additional notes:

On a quality note...the X-Force system is VERY reasonably priced, and is half or a third of the price of alternatives from the USA (PPE, Borla) or Japan (HKS, ISS Forged). But there are some corners cut for the price. Firstly the gaskets are very flimsy, but given the weird hole to boltspacing ratio, I couldn't find alternatives. So they went on with a lick of Permatex Ultra Copper sealant.

This was a little frustrating...whoever welded the resonators together, didn't remove the plastic wrap first. Now the resonators are pressed together and there is no option but to let nature take its course and melt the plastic once we fire her up. There's also lots of nasty paper stickers which take forever to remove. It fits and doesn't leak...but you won't be lying under the car admiring the welding porn.

The only fitment issues to note were very minor: one pipe fouled the diff mount...but when the muffler was bolted up, it pulled the pipe away from it and there's adequate clearance now.

Another was that one of the hangers fouled the aero undertray that bridged the floorpan gap where the driveshafts are. But I made a little hole in it, and now they can co-exist. But apart from those minor issues, the X-Force is a decent product, especially for the price. Unusually, it comes in several short sections (7 in total) instead of one big piece like most aftermarket system do; but I suppose this makes it more feasible to ship, and it also makes installation a bit easier as you're not lifting a huge, heavy section in one go. Being able to bolt up the sections one by one, also makes it more forgiving when it comes to fitment, as you have a little bit of wriggle room where each section bolts up.

Overall the car does feel sprightlier, and the sound of the new exhaust seems to be a good compromise. It burbles at idle, but mostly disappears if the windows and sunroof are closed. The only downside seems to be that the great induction snarl is a little drowned out now. The stock exhaust is so silent that the induction is all you normally hear when the airbox flap opens at 3800rpm...but the exhaust overwhelms it now. But in return, there are all sorts of nice muscle car noises from idle to 4000rpm, so it's swings and roundabouts. Very importantly, it doesn't drone at freeway speeds and there is just a distant woofle...there is a little budda-budda-budda backbeat under load from 1500-2000rpm which is a little intrusive, but I'm thinking that as the system packs out with carbon from use, it might quieten down.

Exhaust note from the outside: http://youtu.be/qp3bryw5BlI

Exhaust note at the track day (from the inside): http://youtu.be/8kemHRZYZLE

Thanks for the DIY write up and review, Babs! We’ll take on your feedback and make sure all those issues you’ve mentioned are sorted out!

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