[-Dan-]

The Basics

No matter which model in the range you have, the first steps to freeing up some extra horses is to get the breathing mods done, and most importantly - done correctly.

By this you should be looking at:

Enclosed Induction kit - Most people claim these to be the best form of Induction for your Saxo, as it's a completely enclosed filter being fed through a Cold Air Feed - direct piping from the front of the car (where the air rushes in) into the filter, which in turn filters all the crap out of the air.

A well known problem is when sitting stationary or not moving these kinds of filters may lack in drawing in the necessary cold air.

These are the most expensive type of filter available, and along with the panel filter, the only type of filter you should consider if looking for decent gains. They can cost anywhere upwards of £90, some going all the way up to £300+

The Panel Filter

A panel filter is a direct replacement for the cars standard filter element and offers superior airflow and better quality materials used. Generally these cost anywhere around £30-40 depending on make, but obviously you can get them more expensive or perhaps cheaper, depending on you budget.

Something worth considering when upgrading to a panel filter, is to get an aftermarket cold air feed, to replace the more restrictive factory piping (especially on the 8v models) and attach to where the 1st jubilee clip clamps onto where the filter is located.

Which you choose out of these two forms of upgraded induction is up to you, and the difference is largely debated. If you are trying to get power on a smallish budget, then the panel filter should be your choice, or If money is no object, then It may be worth considering the likes of the BMC CDA.

The Exhaust System

The Exhaust in Saxos are generally broken down into 3 Separate Sections

The Exhaust Manifold - This is connected to the head and is the first system of exhaust gas exit after the engine. If you open up your engine bay, it is the 4 metal pipes that come out of the head and dissapear off down under the car.

Centre Section - This links the Manifold to the Back Box, and is basically a long straight pipe. It may have a Silencer in, or not, depending on what model the car is etc. (The Silencer will be a box that is in the middle of all the piping)

Back Box - This is the final part of the exhaust system the bit that people see with the tailpipe. It is also known as a Siliencer. It reduces the noise levels, and the exhaust gases flow out of here and out into the air through the tailpipe.

Also

The Catalytic converter - This is a new addition to a exhausts system all cars after 1994 have had to have a cat to pass an emission test at a MoT, it is a box with special materials to filter out harmful elements in the exhaust gases.

It depends on what model and year of car you have, as to where this will be located.

General rule -

All MK1's will have the Cat in the Centre Section (IIRC Y Reg was the first year not to have it here)

All the 8v MK2's (Y Reg onwards IIRC) Will have it in the manifold, and will have either a Straight through centre section (base models) or a pipe with a Silencer in (Furio and VTR)

All VTS's have the Cat in the Centre Section similar to the MK1, even the MK2 VTS's.

So now you know that, your thinking ok, but how do I improve things?

The Basics

The first step to see big Improvements (in terms of breathing mods) will be to De-Cat the car. Depending on what model this will either mean buying an aftermarket Manifold, or an Aftermarket Centre Section. This will give a big improvement on the overall responsiveness of the car.

The Backbox alone won't make barely any difference in terms of power gains, but determines the note of the exhaust tone, and should be a matching bore size to the rest of the exhaust so's to not lose back-pressure.

* - Credit for the following sections go to VTS_16v_Boy - Taken from the 'Exhaust thread'.

*The Centre Pipe - This is basically what it says it is, a centre section with the siliencer removed. This will do two things, greatly improve gasflow and increase noise levels. This is totally legal, as older cars may have only had a single siliencer but as laws and MoTs have changed over the years cars have had to be quiter, so most cars will come with at least one siliencer as well as the back box which is a siliencer. These can cost anywhere between £50-£100 depending on brand and material

*The Manifold - As well as the Cat this is the most restrictive part of a cars exhaust system, some more than others its worth pointing out! By changing the way the gases exit the head and entre the exhaust its possible to change the way the car performs. Most cars have a two peice cast item from new which is heavy and restrive, by changing it to a Mild Steel or Stainless Steel item you can improve a cars performance. These are call 4 Branch as they have 1 pipe per cyclinder so on a inline 4 engine you have 4 branchs or pipes.

*There are two tpes available a 4-2-1 which is 4 pipes that go into 2 pipes that go into 1 pipe which then connects to the exhaust system or Cat, there is also a 4-1 whcih is again 4 pipes but this time all 4 pipes go into 1 pipe which connects to the exhaust system or Cat. The two have a different effect on the way it improves the performance of the car whcih I will explain later. There are manifolds with Sports Cats in them for certain VTR's but these are very expensive with most people choicing to avoid these simply because of high costs.

*Back pressure is created in a exhaust system and the amounts of pressure effect performance. Bigger is not always better, too larger bore in a exhaust system and the gases in the system will lose pressure and the performance of your car will suffer, the same goes for if the bore is too small the gases will be restricted and again performance will suffer. Most aftermarket 'off the shelf' exhausts are the same size bore as the factory item so when buying a sports exhaust of anykind you shouldnt have to worry, but with Custom Exhausts becoming more and more common its improtant to get it right.

Right so If you've now followed me this far - and have upgraded all the components mentioned - your basic breathing mods are done.

I know you won't care about all this and you just want to know how much power your now running?

General rule is If all are done well on a good system you can make UP TO 15bhp, but by no means is this a guarentee.

Of course power gains won't be as high on models such as the 1.1 because the engine is smaller and has less potential.
So your:

1.1 - will have gone from 60bhp to possibly around 70bhp

Furio/Westie - Can get anywhere between 80 and 90 bhp

VTR -
MK1 Models - May see around 100-105bhp
MK2 Models - May see around 105-115 bhp

VTS - Could see potentially up to 135 bhp - but generally breathing is already quite good on the VTS, so gains aren't generally as good as you'd see on a VTR.

Note: These figures are a rough guideline - I'm by no means saying you WILL get this figure - there are far too many variables to consider, but just giving people some sort of ballpark figures to look for.