GR Supra 101: Routes to big power

[Thraxbert]

UYCR is right. A good custom exhaust actually doesn't cost that much more than a good off-the-shelf exhaust system. Oftentimes, the prices are totally comparable.

I slept on this option for a long time thinking it'd be too expensive, but both my turbo cars now have large diameter single exits, and the price was equal to what I could buy in retail.

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[OldHead-MKV-Owner]

Word of advice for those who are tuned on a stock diameter (3.15") downpipe exit with mating exhaust. You WILL need to get retuned if you move to a true 4" exit dp and 4" exhaust.

Granted I'm not stock turbo, but when I switched out my AA downpipe and HKS exhaust for the DAW 5" catless dp with 4" exit (yes, they will make that for you at no additional cost) mated to ETS 4" exhaust, shit got weird. Overboosting, spooled faster, and went back to maxing out the hpfp... all from just changing the dp and exhaust to 4".

It's literally getting tuned today because of the above and I had the FX-400x hpfp and 350ifx injectors installed yesterday.

Hoping to get my new numbers tonight.

 

[Gryph8n]

Yes I already have an Evolution Racewerks 200 cell downpipe but was wondering about Leviathan’s clam that “virtually all exhaust systems reduce down to 3.15” to connect with the factory Downpipe.” And whether that is solved with my 4.5” downpipe or needs a full exhaust to not limit flow?

 

[Gryph8n]

Yes I already have an Evolution Racewerks 200 cell downpipe but was wondering about Leviathan’s clam that “virtually all exhaust systems reduce down to 3.15” to connect with the factory Downpipe.” And whether that is solved with my 4.5” downpipe or needs a full exhaust to not limit flow?

 

[UYCR]

Yes I already have an Evolution Racewerks 200 cell downpipe but was wondering about Leviathan’s clam that “virtually all exhaust systems reduce down to 3.15” to connect with the factory Downpipe.” And whether that is solved with my 4.5” downpipe or needs a full exhaust to not limit flow?

First of all you would have to confirm if your 4.5" DP is a true 4.5". Many DP have larger diameters prior to the connection point to the catback but that is essentially just marketing since the smallest diameter is what determines your flow capacity. This is why going bigger pipe than the turbo exit is also pointless. If the 4.5" DP still steps down to a smaller size to fit the OEM system or OEM compatible systems then your not really solving anything. If it is a true 4.5" then the next possible bottleneck would be in the catback. That is why the Leviathan and other true 4" exhausts split to dual 3" and ensures proper flow.

If you do go custom and want single exit then keep it 4" all the way. If you want dual exit make sure the "Y" is 4" to dual 3". Anything less than that will bottleneck the max flow that the 4" section can have. Dual 75mm pipe would also work for the split but getting metric pipes in the US is not common. (The sum of the cross sectional area for the smaller pipes must be equal or greater than the cross sectional area for the 4" section.)

 

[BrettMRC]

Worth checking it's the ID and not the OD too!

 

[EddieNel]

I would love to see a comparison of different exhaust and dyno numbers. Naturally your going to live some number if your wanting to go quieter the a super high flowing loud exhaust. Definitely something to think about when making an exhaust choice. I know I am.

 

[razorlab]

I would love to see a comparison of different exhaust and dyno numbers. Naturally your going to live some number if your wanting to go quieter the a super high flowing loud exhaust. Definitely something to think about when making an exhaust choice. I know I am.

Agreed. All the claims I have seen so far have been like “we removed the oem DP with oem cat and made a bunch of power”. Well duh.

 

[UYCR]

I would love to see a comparison of different exhaust and dyno numbers. Naturally your going to live some number if your wanting to go quieter the a super high flowing loud exhaust. Definitely something to think about when making an exhaust choice. I know I am.

Many resonators and straight mufflers don't really disrupt the flow much so it might not affect the numbers as much as you might think. Even having a properly sized high flow cat can net very similar power to a catless system. The whole exhaust just won't be as light as a straight pipe but no drone is a win on this engine.

 

[EddieNel]

Many resonators and straight mufflers don't really disrupt the flow much so it might not affect the numbers as much as you might think. Even having a properly sized high flow cat can net very similar power to a catless system. The whole exhaust just won't be as light as a straight pipe but no drone is a win on this engine.

The drone is huge for me. I travel a lot with my car. Basically replaced my RoadGlide with this car so I like taking trips in it. Hopefully I’ll have my turbo and port injection installed in the next 6 or so months so I know exhaust will be next. I’m catless with the factory exhaust but I’m curious how bad it’s going to hurt my overall numbers. That being said I plan on a conservative tune but I’m still wanting 700 wheel.

 

[UYCR]

The drone is huge for me. I travel a lot with my car. Basically replaced my RoadGlide with this car so I like taking trips in it. Hopefully I’ll have my turbo and port injection installed in the next 6 or so months so I know exhaust will be next. I’m catless with the factory exhaust but I’m curious how bad it’s going to hurt my overall numbers. That being said I plan on a conservative tune but I’m still wanting 700 wheel.

Not sure how many videos of the Leviathan you may have watched but @Alec-RemnantPerformance made a few just cruising and it is a deep but subtle exhaust note. Seems like a very daily drivable system and you can adjust how much you quite it down. Obviously when you step on it it's a different story but if you want to go with something you can just buy I'd suggest looking into it more. I'm eventually going custom route but will be something very similar to the Leviathan with a Gesi 850HP cat, Vibrant resonators/mufflers, and possibly going titanium depending on the price difference.

 

[OldHead-MKV-Owner]

Not sure how many videos of the Leviathan you may have watched but @Alec-RemnantPerformance made a few just cruising and it is a deep but subtle exhaust note. Seems like a very daily drivable system and you can adjust how much you quite it down. Obviously when you step on it it's a different story but if you want to go with something you can just buy I'd suggest looking into it more. I'm eventually going custom route but will be something very similar to the Leviathan with a Gesi 850HP cat, Vibrant resonators/mufflers, and possibly going titanium depending on the price difference.

I mentioned above that I'm running a DAW catless true 4" exit. I wasn't sure if I could handle the additional smells of going catless but it doesn't bother me at all and really isn't that bad.
I bought this after I bought the ETS full setup. That is their catted downpipe with 4" exit and their 4" exhaust. I've never even installed the ETS downpipe. I'd be happy to part with it for a reasonable offer if someone wants it.

 

[OldHead-MKV-Owner]

Oh, and it's literally (finally) on the dyno right now. Sameh is finishing up the 93 map. Flex is next and he's targeting E65-75. The local pump is constantly around E75 but there will probably be a little 93 left in the tank, which will obviously dilute E mixture.

 

[UYCR]

I mentioned above that I'm running a DAW catless true 4" exit. I wasn't sure if I could handle the additional smells of going catless but it doesn't bother me at all and really isn't that bad.
I bought this after I bought the ETS full setup. That is their catted downpipe with 4" exit and their 4" exhaust. I've never even installed the ETS downpipe. I'd be happy to part with it for a reasonable offer if someone wants it.

I was planning on getting V-bands for everything but I'll keep it in mind. Just having to modify the DP would certainly make it easier for the shop and possibly my pocket at the end of the day. If you can, DM me some pictures just so that I can also check the specs on the cat since their website doesn't state which one they use.

 

[OldHead-MKV-Owner]

Will do. I'm on vacation and will be back tomorrow. Will send pictures this weekend.

I was planning on getting V-bands for everything but I'll keep it in mind. Just having to modify the DP would certainly make it easier for the shop and possibly my pocket at the end of the day. If you can, DM me some pictures just so that I can also check the specs on the cat since their website doesn't state which one they use.

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