ive been thinking about adding some sort of charger on my 98 SR5 4runner but im not quite sure what, im not trying to do anthing too expensive. i know that superchargers are expensive but are they actually worth the money ?

I think I want to supercharge, but my engine and trans have 250k miles on them.

I think id spend the money on a rebuild of those first.

Hunt junkyards and car-part.com and see if you can snag a used one. $3500 for a new one just isn't worth it anymore, not when some 4Runners on the road aren't even worth that much!

My 4Runner enjoyed somewhere around 150K miles of supercharged fun before it started to show some wear. The extra heat from the charger will cause the valves to wear down a little faster, nothing dramatic but it does happen. More prone to cracked valves too if you really beat on it often. As far as the transmission goes, the supercharger puts out a lot more heat in the engine (normally comes with a 170* thermostat vs 190* stock) and this heat is also increased in the transmission. A good quality synthetic transmission fluid with frequent checks will keep it running smoothly. There's no inherent risk to the transmission other than heat.

My experience has been is if the compression is good in all cylinders and is mechanically sound, mileage doesn't matter. If you have cylinders with low compression or other issues, the supercharger will exacerbate them.

Is this actually a TRD supercharger, i.e.: a Toyota part that doesn't void warranty? I can't find where to buy one, only people talking about it.

I feel extremely confident saying that all 3rd gens no longer have any warranty from the manufacturer or dealer so this is a non-issue.

But what about that extended vehicle warranty that I'm always getting calls about?

I’ve been trying to waste their time for years. Apparently my 4Runner is too old lol they always hang up once I tell them the year/make/model which is rude!

Since adding a TRD supercharger I now know that my 4R has
a 108 mph speed limiter, and it works!

TRD dropped their supercharger line about 6ish years ago. Magnuson, the original manufacturer (Toyota didn't ever make the supercharger) makes it without the logo. Here's a link to their online store: MP62 Toyota 5VZ-FE 3.4L V6 Supercharger System – Magnuson Superchargers.

I'll warn you now though, the recent price hikes makes the supercharger not worth it anymore. You are better off buying a 4Runner with one already installed. $4,000 after taxes is straight up robbery. For reference when I bought mine, most 4Runners were going for about $5500 with 200K miles in good condition and I paid $7000 for mine, so you could say I paid a $1500 premium for the benefit of a supercharged engine. In today's market I would expect that premium to be around $2000 extra.