[John XT]

Hi all,

In the next couple of weeks I will install to my EUDM Forester XT 2.0:
helix uppipe
invidia downpipe
prodrive muffler
sti injectors
sti intercooler
ecutek
and the question is, replace the stock turbo TF035 with a td04 or vf35? (i have both of them).
I use this car everyday and its more important to me to have low end power than to loose top end 20whp. The difference at the torque will be significant?

Thanks

 

[stevem]

Skip the td04 - go straight to the VF35.

I've gone td04->vf35 and there is a wall of torque, even before an 'optimal' map..

Check your uppipe isn't a bigger diameter than the stock one - it will kill your low-end performance.

Rgds
Steve

 

[John XT]

Skip the td04 - go straight to the VF35.

I've gone td04->vf35 and there is a wall of torque, even before an 'optimal' map..

Check your uppipe isn't a bigger diameter than the stock one - it will kill your low-end performance.

Rgds
Steve

I diden't bought the up & down pipe yet, any suggestions pls?

 

[stevem]

If your uppipe isn't catted - stick with the oem one. If it is , go with a same diameter ( 51 mm ? ) , make it stainless and wrap it.

Downpipe anything with an open neck and no cats ( or a sportscat at least )

Can't really advise on the make as I don't know what's available locally

rgds
Steve

 

[John XT]

My uppipe is cated, and i will replace it with a catless...
I'll keep a high flow metalic racing cat in the downpipe, I want to be "legal" and respect the environement.
I buy from everywhere, usualy from the US marquet, as the costs with shippment and taxes are the same.

If i use a big diameter uppipe, the velocity of the gases in the uppipe will decrease, wich will make the turbine to spool later, is that correct? but I will gain something in the really low rpms, before the turbo spoolup?

 

[stevem]

My uppipe is cated, and i will replace it with a catless...
I'll keep a high flow metalic racing cat in the downpipe, I want to be "legal" and respect the environement.
I buy from everywhere, usualy from the US marquet, as the costs with shippment and taxes are the same.

If i use a big diameter uppipe, the velocity of the gases in the uppipe will decrease, wich will make the turbine to spool later, is that correct? but I will gain something in the really low rpms, before the turbo spoolup?

Try Hayward & Scott for a sportscat downpipe & matched uppipe then

www.scoobyexhausts.com

You are correct that the larger dia uppipe will delay spooling, but the gain in very low rpms isn't significant enough to justify it. If you want to get some low end torque back you could port the headers out to the gasket ring at the head ends and up pipe joint. Can be done relatively easily with an air grinder...


rgds
Steve