N75J solenoid.

[seangti]

Other than the valve; what else is there to change, that will allow more fun?
Looking at the I/C to T/B, and TIP, downpipe, followed by a tune for power, then suspension and brakes for the necessary safety aspect; what are the usual do's and don'ts with these cars?

How deep are your pockets? I started with suspension before any power.

For a tuned car I'd follow the path of the air. So air intake, either a DIY style, check out H100vw's (Gavin) build thread, pod form or a PD160 which is off a diesel Seat Cupra from recollection. It looks factory, but is larger than stock.

People have argued whether a turbo intake pipe (TIP) is the next best thing for bang for your buck, each to their own. I support the mod.

Consider your diverter valve, if it's stock you'd likely want to replace to ensure boost is kept under control.

FMIC - SeatSport are popular, Forge are ok. There are some very similar to SeatSport, just with thicker cores. Use the forge fitting kit or source parts elsewhere.

Then downpipe. A downpipe will require a new tune as it'll otherwise throw codes. Cat back won't gain bulk power, but a nice to have, DP will gain better results.

At this point you're be at around 140kwat. A perfect balance of power, reliability and drive-ability.

From here, bigger turbo, injectors, fuel pump, FPR, more tuning, etc, etc.

[seangti]

Personally I'd do 3' downpipe +cat if money tight or full system if you have $, a retune to suit, then intercooler and then you'll probably want to spend money on not sliding off the road (dampers, bars, springs). You can waste a lot of money on plugs, DV's, silicon pipes, overrated CAI's - its all diminishing returns type expenditure really. Do the big stuff first.

haha, between Sam and I, we've just nailed the two trains of thought at different ends. Sam's approach will give biggest bang for buck, though as I track my cars regularly, I'm more comfortable with the air-in, air-out approach given the driving conditions. For street driving, each to their own. I like to have the supporting mods in place to optimize the bigger ticket mods. I wouldn't say one is more right/wrong than the other though.

[amdeman]

Personally I'd do 3' downpipe +cat if money tight or full system if you have $, a retune to suit, then intercooler and then you'll probably want to spend money on not sliding off the road (dampers, bars, springs). You can waste a lot of money on plugs, DV's, silicon pipes, overrated CAI's - its all diminishing returns type expenditure really. Do the big stuff first.

Thanks for your input.
A 3" downpipe? That sounds large with such a small turbo?
I've already done a 2.5" mandrel bent exhaust (resonator and muffler was left over from the previous car).

[h100vw]

Thanks for your input.
A 3" downpipe? That sounds large with such a small turbo?
I've already done a 2.5" mandrel bent exhaust (resonator and muffler was left over from the previous car).

You might think that but it's not a downside. If you decide to go for a turbo change later, no need to redo the downpipe.

Gavin

[sambb]

Yeah 3'' dump isn't too big even for a K03. I agonised over whether to go 2.5'' or 3'' after reading stories about losing bottom end with the bigger pipe etc. I can honestly say I cannot fathom how anyone could say the 3 '' sacrifices bottom end. Mine spools so fast from so low, its too responsive down low if anything. Only prob with 3'' is that you cant just buy off the shelf dumps - it'd need to be a custom job. But 3'' feeding into your 2.5in system post cat would be awesome.

[amdeman]

Yeah 3'' dump isn't too big even for a K03. I agonised over whether to go 2.5'' or 3'' after reading stories about losing bottom end with the bigger pipe etc. I can honestly say I cannot fathom how anyone could say the 3 '' sacrifices bottom end. Mine spools so fast from so low, its too responsive down low if anything. Only prob with 3'' is that you cant just buy off the shelf dumps - it'd need to be a custom job. But 3'' feeding into your 2.5in system post cat would be awesome.

3" with cats?

[louis19]

You might think that but it's not a downside. If you decide to go for a turbo change later, no need to redo the downpipe.

Gavin

Great advise, I went with a 2.5" to begin with into the standard catback, then ended up wanting a 3" afterwards and now have a full 3" system. I made some of my money back on the 2.5" when I sold it but if I had my time again I would be go 3" straight up, cost wise it will be only slightly more expensive, noise wise it's almost identical and leaves you with the option to go a bigger turbo later on if you decide too.

[sambb]

sorry your in NZ aren't you. you're cat exempt for that year polo maybe?? if so, straight 3'' dump coned down to 2.5'' back where the gases have cooled off.
Yeah as far as starting mods with the exhaust vs ending with it, I always figured that the biggest limitation of the motor was the perceived small size of the turbo, but this is as much of a function of all that backpressure not allowing it to breathe to its full potential. With the exhaust opened up you get peak HP, cooler EGT's, quicker spool, better fuel economy etc. and all the other mods have more value once the exhaust is done. ie a TIP done pre exhaust would barely be felt in contrast to if done afterwards. But yeah you can come at it from the other side and say that inlet air temps are a bigger issue and after an IC the combustion temps will drop and give you more power and less egt that way. I guess doing IC first will give the car more grunt within the realms of its existing spool/power band - doing the exhaust will actually change the spool/ peak hp band completely and let the car stretch its legs more. kind of chicken or the egg really. If its only warm 3 months of the year where you are that may influence your decision?

[amdeman]

Great advise, I went with a 2.5" to begin with into the standard catback, then ended up wanting a 3" afterwards and now have a full 3" system. I made some of my money back on the 2.5" when I sold it but if I had my time again I would be go 3" straight up, cost wise it will be only slightly more expensive, noise wise it's almost identical and leaves you with the option to go a bigger turbo later on if you decide too.

Do it once, do it right, correct?

[amdeman]

sorry your in NZ aren't you. you're cat exempt for that year polo maybe?? if so, straight 3'' dump coned down to 2.5'' back where the gases have cooled off.
Yeah as far as starting mods with the exhaust vs ending with it, I always figured that the biggest limitation of the motor was the perceived small size of the turbo, but this is as much of a function of all that backpressure not allowing it to breathe to its full potential. With the exhaust opened up you get peak HP, cooler EGT's, quicker spool, better fuel economy etc. and all the other mods have more value once the exhaust is done. ie a TIP done pre exhaust would barely be felt in contrast to if done afterwards. But yeah you can come at it from the other side and say that inlet air temps are a bigger issue and after an IC the combustion temps will drop and give you more power and less egt that way. I guess doing IC first will give the car more grunt within the realms of its existing spool/power band - doing the exhaust will actually change the spool/ peak hp band completely and let the car stretch its legs more. kind of chicken or the egg really. If its only warm 3 months of the year where you are that may influence your decision?

Awesome!
Great advice, this has been the big dilemma; chicken / egg scenario.
Exhaust is where I've always started on any build, and the down pipe IS part of the exhaust...

Watch this space.

That or, time to be responsible and hit the safety stuff, like brakes and handling next. Going fast is one thing, being able to do it and stop or manoeuvre is preferred.