A friend has a 1.5 120hp focus mk3.

The car is remapped.

He is going to change the air filter box with a st one.

What could be changed to exhaust for better performance?

ST airbox is same as the 1.5 tdci

16 minutes ago, Bol said:

What could be changed to exhaust for better performance?

Nothing, diesels don't work like that

Hypothical question.

Dpf delete and free flow muffler couldnt increase performance a bit (3-5 hp)?

13 minutes ago, DaveT70 said:

ST airbox is same as the 1.5 tdci

Nothing, diesels don't work like that

I think the 1.5 diesel's airbox is the same as the 1.0

That's why he wants to change it.

What about larger diameter exhaust pipe?

 

1 hour ago, Bol said:

I think the 1.5 diesel's airbox is the same as the 1.0

Which is the same as the ST

Only the RS had a different lid on the airbox, same airbox and filter

56 minutes ago, Bol said:

What about larger diameter exhaust pipe?

Diesels don't work like that, remapping will get the best.

CAT and DPF will help a little bit, but the remap will be better

Gearbox is weak on 1.5 TDCi, be careful

So larger exhaust pipe wouldnt increase performance.

 

I mean the second pipe that connects to air box.

Also rs's lid is different as you mentioned.

Thank you.

Seriously, just remap it, with a good remap and it will be much better

It is already remapped. It is a friend's car.

He wants even more performance increase.

Perhaps i will tell him not to change anything at the exhaust or to change the pipe and the muffler only.