oslo

I'm not sure about the most recent model years, but in the past the "lexus premium audio system" has been made by pioneer.

I know that in the LS400 and ES300 the factory amp is separate from the head unit. In these cars it is located underneath the passenger seat. I'm guessing the RX300 has a separate factory amp as well. An amp rewire probably refers to extending the speaker wiring harness from the factory amp to the location of the head unit. In my LS400 I soldered together my own wiring harness that went from beneath the passenger seat up to my new head unit. Fair bit of work, but definitely worth it.

The factory sub only gets 40-50 watts so putting in a new subwoofer may improve the bass a little, but you won't notice any big improvement until you install a new amp as well. The drawback of this is that you will need to run a power wire from the battery to the trunk, which can be difficult, especially if it's your first time doing it.

It's possible. You have a couple of options available. You can either find a wiring harness that will wire in behind the head unit and act simply as an audio cable which will carry the signal to your factory amp (which is underneath your passenger seat), or you can get a wiring harness that will plug into the speaker wire harness that is currently plugged into the factory amp. The second option will give you better sound quality, as it will take power from the amp that is built into your new head unit, but you will have to create a custom wiring harness that runs from underneath your passenger seat to the factory head unit location. I had to do this in my LS400, so if you have any questions feel free to ask.

Very nice. I, myself have a '98 and it's an amazing car. It's sure to treat you well, especially with it being so well maintained. Congrats!

Matched up all the positions marked on the instructions and everything seems to be working fine. Car has a boatload of power now. This weekend I'll take some photos of everything (After I give the car a nice wash first, of course).

what are your plans for the custom springs? any chance you'll sell 'em?

I *may* have pulled mine off.

Anyone know the purpose of the insulation under the hood? My assumption is that it's for sound insulation, but I have also heard that it acts as a fire blanket, smothering an engine fire.

Okay, talked to SRT and they told me that while the wire colors may not match up for the LS400, their positions will be the same. Also, sensor 1 is the mass air flow sensor, and sensor 2 is the throttle position sensor. I will wire up the ECU tonight and confirm this information.

I gave them a call the other day and they told me they don't install the chip onto the LS400. Because of this, they weren't able to give me any better instructions. I did however find a wiring diagram through the automotive hobbyists digital online library. I'm going to give swift another call today and find out what sensors are referenced in the instructions they provided, and hopefully along with the diagram I found I should be able to get things wired correctly. I'll keep you posted on my progress and get some pics of the intake up too. (btw, I noticed also that the chip lists the LS400 and the SC400 as well)

you could always use a line out converter with the factory sub wires.

Unfortunately I do not know which two sensors the instructions refer to.

these wires

I searched the forum and the web thoroughly for an ECU wiring diagram for a 98 LS, but so far I have only come across the gen I ECU diagrams. I'm installing an SRT high flow intake system originally designed for a GS400, so my directions don't quite match up. Any help would be appreciated. I'll post some pics of the intake once all is said and done.