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Discussion Starter · #1 ·
There seems to be a lot of "it won't work" on this forum in relation to 93-98 Supra long tube headers on a 2001-2005 IS300. I have read every single post related to the topic and performed multiple searches.

Has anyone actually tried?

The reason for this post, is I have been told by 2 folks that they fit fine and "they knew a guy that did it, needs a couple of small mods".

I am aware that the collector is a single outlet pipe, not a big deal if you are building a full exhaust.

I see that I'd have to add a couple of sensor bungs, again not an issue.

Though there was concern about the collector location contacting the firewall by someone on here.
 

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Discussion Starter · #4 ·
There really isn't anything wrong with a header designed specifically for an IS300 - but there is typically a significant cost delta in most cases between the 2 (and I may have the option for a free used Supra header - which may require the above mentioned work).

The main issue for me is, I have decided to utilize my IS300 as a daily, it has far better mileage (easier to park, handles better, and has better road feel) than my 6.7 Diesel Ram. If the Supra header doesn't work, I don't really want to have to put the old exhaust back in to be able to drive the next day (with wasting money on new gaskets, to have to replace them again with another set of headers). Buying an IS300 header just in case the Supra header doesn't fit is somewhat counter productive.

Whats wrong with a header for an is300?
 

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It's the same engine so it should bolt up fine. Your issue would probably when it runs back to the midpipe, it's not the same as the IS300 so mods will be needed. Also the angle it'll be sitting at, might not line up.
 

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There really isn't anything wrong with a header designed specifically for an IS300 - but there is typically a significant cost delta in most cases between the 2 (and I may have the option for a free used Supra header - which may require the above mentioned work).

The main issue for me is, I have decided to utilize my IS300 as a daily, it has far better mileage (easier to park, handles better, and has better road feel) than my 6.7 Diesel Ram. If the Supra header doesn't work, I don't really want to have to put the old exhaust back in to be able to drive the next day (with wasting money on new gaskets, to have to replace them again with another set of headers). Buying an IS300 header just in case the Supra header doesn't fit is somewhat counter productive.
So its your daily and you're worried about something custom and not being able to drive the next day if there's an issue, but know the supra headers would require customization to work.
You should also be considering what it costs to do any custom work to the supra header flange + your exhaust and weigh that against what a set of IS300 headers cost.
If you're going the ebay header route, that cost difference is probably a wash. It would require minimal time to install, no risk of nothing fitting, and no further modifications to exhaust/firewall/etc.
 
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Discussion Starter · #8 ·
I have other vehicles to drive, I would rather keep this as a daily. A weekend or even a week off the street isn’t that bad. I have another project car that’s been off the road for 6 summers, and is finally close - started as a quick, heads, cam, intake build and snowballed. It’s really nice though. 😂

The cost of custom work is materials only for me, the cost of time is my own personal “spare time”.

So its your daily and you're worried about something custom and not being able to drive the next day if there's an issue, but know the supra headers would require customization to work.
You should also be considering what it costs to do any custom work to the supra header flange + your exhaust and weigh that against what a set of IS300 headers cost.
If you're going the ebay header route, that cost difference is probably a wash. It would require minimal time to install, no risk of nothing fitting, and no further modifications to exhaust/firewall/etc.
 

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Discussion Starter · #9 ·
It’s more than just a gasket; buying the same gasket in the same month because a product doesn’t fit is ridiculous to me. Especially when now I still have to buy another header.

What I’m gaining from this thread is no one has actually tried a supra header, and I’m better off not being the first. I’ll just end up ordering a header for the car I guess.

Sounds like you have the stock cats for the car already. Why not just put those on and drive the car. You’re complaining about spending a very small amount of money on an exhaust manifold gasket.
 

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…If the Supra header doesn't work, I don't really want to have to put the old exhaust back in to be able to drive the next day (
So it sounds like you already have the stock exhaust manifolds on the is300 already? If so why go through the trouble trying to put a soopra header on? Just leave it alone 🤷🏽‍♂️
 

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SUPRA HAS A DIFFERENT ENGINE BAY EVEN WITH THE SAME ENGINE. PLUS MIDPIPES DIFFERENT. ITLL "FIT" BUT NEED WORK IF IT DOESNT HIT ANYTHING ON THE WAY IN
 
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