How much can I mod stock setup WITHOUT having to upgrade fuel etc?
 

I just had a look at the prices for all the stuff I need for a decent power upgrade and converted to Aussie dollars its big bucks! AFC is about $1,000Aus. Upgrade radiator about $1,000. Buggered if I can spend $1000 on a radiator before I even start on the real (fun) mods! The FCD is $219 here so I will get that just incase, but I am realistically only going to be able to afford to get the exhaust done (my mate is going to make it from scratch so it will be practically free!). We will only do enough of the exhaust so that we get a decent raise in the boost without going so far that we need to upgrade the fuel system or port the wastegate (S4). Question for everyone: How much boost do you think we should aim for so that we don't reach the point where other stuff needs upgrading? I was thinking 9psi would be ok????? I really need a final word on this so I can stop worrying and get started. Thanks.

I think with only a bigger downpipe/midpipe with stock catback and stock filter you would be okay but even then I would rewire the fuel pump. Just save money and buy a walbro hi flow and don't forget to port the s4 wastegate ;)

what does rewiring the fuel pump mean? Why would it be wired wrong in the first place? I have been trying to get an answer to this for ages.

Its not that its wires wrong, its just that the fuel pump is such a critical part of the engine's health under heavy load/boost that most people like to do this mod to be absolutely sure the pump sees max voltage at all times, because the stock wiring can deteriorate over time. I have measured a 1 volt difference fromt eh battery to the pump. Hell, Ive measured more than 1 volt difference from the alternator output to the battery. Same with the hesitation/grounding issues...stock connections and wiring deteriorates.

Also the t2 has a regulator solenoid that keeps pump voltage down around 10v at normal driving, and raises it to full power(or as close as it can) only when under boost.

the point is to make sure you have full voltage at the fuel pump. with old wires and relays the voltage can drop off. even worse with the lights and stereo on etc. the pump should see 14 volts. people have seen it drop to 10 volts under throttle. that means the pump is working at 70% power. and is pumping 30% less fuel then it should. it needs full voltage to work at full load.

that lack of fuel can cause it to run lean and detonate.

thanks for those explanations! That's helped heaps. So do you think 9psi will be ok if I get the fuel pump rewired?

anyone? 9psi?

the problem is being able to limit yourself to 9psi. just an exhaust will put you over that. you really need to port your wastegate to keep it down.

Hes right, its not limiting the car to 9psi, its limiting yourself to 9psi! :p:

I dont think I will go from 5.5 psi (stock) to over 9psi if I only do a part of the exhaust such as downpipe or catback and maybe TID mod. I can just do enough to get me to 9psi can't I? If I do end up having to port the wastegate, how will I know how much to port it so that I don't loose all the boost I just created by doing all this in the first place? I guess I could buy a boost controller but thats an unnecessary expense if I can just get the 'safe' boost I want straight off. Any thoughts on that?

And its my finite cash flow that is limiting me. I work freelance as a graphic designer and these few months before the start of the new business year are very slow. No work.

just trying to confirm here w/out a ported wastegate but with a high flow fuel pump and the 3'' HKS DP with STOCK catback am I really going to be in danger of leaning out or getting boost spikes/creep

is it worth rewiring the stock fuel pump when wanting to run alittle higher boost, 10 for example?

the best thing you can do is get a A/F gauge and find out for yourself :)

I doubt you'd have to worry much about leaning out with the hi-flow pump but you might have to worry about boost spikes/creep, so a boost gauge would also be a good idea.