Exhaust decat

[Guest Chrisember]

Hi everyone,

 

Sorry for posting tech questions so soon after joining the club but I am desperate to get going and begin making tidying up and releasing a little more power on my latest purchase!

 

I bought a UK spec 1995 Supra TT with 98K on clock. I have had a look under her today and she still has standard exhaust system. I would like to put on the 1st decat pipe but have a few quesitons. I am going to purchase a boost gauge at some point but will I get away with putting the 1st decat on first or do I risk raising the boost too much?

 

I see there are 2.5" and 3" decat pipes, does anybody know which one is a direct fit for the UK spec TT Supra?

 

Will putting the 1st decat pipe on hurt the 2nd decat or is it pointless when I still have the standard cat back? (I do intend on chaning the cat back once I have more pennies!)

 

Any advice would be much appreicated.

 

Cheers, Chris.

[Guest Chrisember]

Hi again!

 

I have been using the search button for the last two days and am really struggling to find out if the 1st and 2nd decat pipes differ between jap and uk spec tts. It seems the 1st decat is different but can anybody tell me how? I cant figure out why there are 2.5 and 3" versions!!????

 

Also I now see that some 2nd decats have a flange for a lamda sensor. Is it necessary to fit a lamda sensor on the decat?

 

Anybody got any the 1st and 2nd decats (for UK model) for sale?

 

Cheers,

 

Chris.

[Homer]

The first cat difference between the Export and Jspec is due to the flange between the 1st cat and the collector from the manifold & EGCV. They are not interchangable.

 

It really doesn't matter whether it's 2.5 in or 3in, there won't be any noticable performance difference on stock turbos.

 

The sensor on the 2nd decat is used for the 2nd O2 sensor on the exports (The jspec does not have a 2nd O2 sensor). On the Jspecs it is simply blanked off, or ideally used to fit a wideband O2 sensor for an AFR gauge.

 

Have a read here before de-catting: bpu

[Guest Chrisember]

Thanks Homer, I take it then that I will need to reinstall the stock sensor in the 2nd decat or the ECU will get the fuelling wrong? Do you see any issues with me installing both decat pipes without any of the other BPU mods? I am going to do them all but I dont have the money to do them all at once!!

 

Thanks for your help.

[Homer]

Thanks Homer, I take it then that I will need to reinstall the stock sensor in the 2nd decat or the ECU will get the fuelling wrong? Do you see any issues with me installing both decat pipes without any of the other BPU mods? I am going to do them all but I dont have the money to do them all at once!!

 

Thanks for your help.

 

Have a read of the BPU thread to get a full picture.

 

Yes, you need to order a UK spec 1st decat pipe and a 2nd decat with the boss for the 2nd O2. Some people report that the UK's run okay without the 2nd decat but personally I'd never do that.

 

The UK spec will only run marginally more boost with a decat and should be fine without making the other BPU mods

 

However if your intention is a power increase and improved engine response you really need to get an some colder plugs, FCD and a boost controller to get it moving. It is a very considerable difference once the boost is raised to over 1.1 bar.

 

Now is a good time to consider your cars service items before going for more boost, primarily the IC condition (needs to be in good condition, a stock original one will likely be beyond it's serviceable use), plus fuel pump as the potential 17 year old one will likely be past it's best.

[Oddball87]

what is the sensor in the first cat? its wiring go's up into the drivers side

floor well. thanks

[Oddball87]

my supra is a tt jap

[Nic]

what is the sensor in the first cat? its wiring go's up into the drivers side

floor well. thanks

 

Heat sensor for the cat overheating warning light on the dash. It has no effect on performance and can be just cable tied out of the way.

[Oddball87]

thanks mate