Ok...Let me try and shed a little light on the subject...
First off, the 527, 577, and 682cc injectors are all that mopar has come out with to help us safely build power. Unfortunately they forgot to add a factory returnline in the mix to control the injectors. They just used the pcm's injector duty cycle and figured that would be enough. For most people, that's more than enough, but when you're only limited to a maximum of that particular size injector you may find yourself running out of fuel very quickly when raising the boost or going with a larger than stock turbo. Before I forget, let me point out that a wideband and/or a scangauge are very critical when playing with fuel or boost. If you don't know how lean you are running it could be over for your motor within a matter of seconds. On the flipside, if you don't know when your injectors are nearing their max potential also known as injector duty cycle (IDC) unless you have a scangauge to monitor it.
There are several different aftermarket injectors for our cars as well. Most of these are meant for much larger horsepower applications. 650s will support 470whp, 750s will support over 500whp. BUT...you can't just slap these in and make that kind of power on stock fuel pressure levels. The fuel pressure has to be raised in order to reach the max potential of these injectors and it's the same with the mopar injectors. Stage 1 injectors have seen as high as 330 +/- and S2/S3 injectors have seen almost a hundred more horsepower than that. Again, you cannot reach those numbers on stock fuel pressures, you'll run out of fuel well before that point.
This is where the returnlines come into play. You can manually adjust your fuel pressure to either raise or lower it depending on the size of your injectors. One might ask, "why would I want to lower fuel pressure, you just said you need more pressure to make more power." While this may be correct, we also have this thing called rising rate, or boost reference. Rising rate means that your fuel pressure will raise in conjunction with your boost pressure. The best known ratio for our cars thus far is 1:1 meaning for every 1 psi of boost, the regulator will raise the fuel pressure by 1 psi as well. If your fuel pressure at idle is 50psi and you're boosting 20psi, you will end up with 70psi of fuel pressure. This is a very popular choice for those with injectors like the 750s. Setting a higher fuel pressure without the 1:1 source can cause stumbles and driveabillity issues because it's just too much fuel for the computer to trim off in order to reach it's target afr of 14.7. So most guys will lower the fuel pressure to make it easier for the computer to adjust for it's target afr and hook up the rising rate to add fuel pressure when in boost. Have I lost you yet?
Next on the list...now that you have all this fuel, you have to be able to control it. You do this with your mapclamp, safc, or dtec. Essentially what these do is alter the amount of boost the computer sees to give you less fuel at a given rpm point. For example with a mapclamp, you're clamping a certain voltage based on map signals. The pcm will start to drop timing in order to prevent damage to your engine if it sees more than it's max boost level. On S0 and S1 cars this happens to be just a tad over 18psi. On S2/S3 computers I believe it is upped to 24psi. By using a mapclamp, you can fool the computer into thinking you're only running 14psi as an example (you can select any psi you want based on your voltage). If the computer is only seeing 14psi and you're running 20psi, the computer will only give you enough fuel to safely opperate on 14psi. Since you're running more boost than 14psi you will have less fuel than what's recommended and it will lean you out. This is a good thing because you can make more power this way, but you have to be careful not to lean out too much.
Safcs work the same way, only instead of being only 1 clamp, you now have 12 clamps and they're user adjustable. You can place them anywhere you want in the rpm range and set them at any voltage you want based on percentages instead of volts. As an example, you can pull out 20% fuel instead of having to run say 4.37v and you don't have to do the math to figure it out. However, there is a chart floating around somewhere that tells you what voltage correlates with what boost level so you don't get too confused with it. You may also choose what rpm points you want to use as well like I stated above. This means you can spread out your rpm points and take away fuel based on how lean or rich you are running throughout the powerband. A mapclamp can only pull one amount away across the whole rpm range, an safc can pull several different amounts away at any rpm range. Hope this clears some things up for you.
To answer a few of your questions directly, you can use either S1 injectors and a returnline to make 300whp, or you can use S2 injectors without the returnline. Both combinations will provide enough fuel for that amount of power. Your stock fuel pump can only supply so much volume and it doesn't last long when it's being overworked. A larger fuel pump will supply more volume, not more pressure. You'll still be working off of your stock 58psi or you can raise/lower the pressure via a returnline. It is NEVER too early to add a fuel pump as it is cheap insurance incase you start reaching the limits of the stock fuel system.
A bottleneck fix is something that is commonly done when using a returnline. Essentially this completely removes the stock fuel pressure regulator out of the loop that's set for 58psi from the factory. It also gets rid of the garbage that DCX was nice enough to supply us with that's simply not large enough to flow the amount of fuel needed to make high horsepower. The stock fuel pressure regulator necks down pretty small and we simply can't move enough fuel through it. By going with the bottleneck fix we eliminate this problem and we are able to provide more fuel to the injectors safely.
First off, the 527, 577, and 682cc injectors are all that mopar has come out with to help us safely build power. Unfortunately they forgot to add a factory returnline in the mix to control the injectors. They just used the pcm's injector duty cycle and figured that would be enough. For most people, that's more than enough, but when you're only limited to a maximum of that particular size injector you may find yourself running out of fuel very quickly when raising the boost or going with a larger than stock turbo. Before I forget, let me point out that a wideband and/or a scangauge are very critical when playing with fuel or boost. If you don't know how lean you are running it could be over for your motor within a matter of seconds. On the flipside, if you don't know when your injectors are nearing their max potential also known as injector duty cycle (IDC) unless you have a scangauge to monitor it.
There are several different aftermarket injectors for our cars as well. Most of these are meant for much larger horsepower applications. 650s will support 470whp, 750s will support over 500whp. BUT...you can't just slap these in and make that kind of power on stock fuel pressure levels. The fuel pressure has to be raised in order to reach the max potential of these injectors and it's the same with the mopar injectors. Stage 1 injectors have seen as high as 330 +/- and S2/S3 injectors have seen almost a hundred more horsepower than that. Again, you cannot reach those numbers on stock fuel pressures, you'll run out of fuel well before that point.
This is where the returnlines come into play. You can manually adjust your fuel pressure to either raise or lower it depending on the size of your injectors. One might ask, "why would I want to lower fuel pressure, you just said you need more pressure to make more power." While this may be correct, we also have this thing called rising rate, or boost reference. Rising rate means that your fuel pressure will raise in conjunction with your boost pressure. The best known ratio for our cars thus far is 1:1 meaning for every 1 psi of boost, the regulator will raise the fuel pressure by 1 psi as well. If your fuel pressure at idle is 50psi and you're boosting 20psi, you will end up with 70psi of fuel pressure. This is a very popular choice for those with injectors like the 750s. Setting a higher fuel pressure without the 1:1 source can cause stumbles and driveabillity issues because it's just too much fuel for the computer to trim off in order to reach it's target afr of 14.7. So most guys will lower the fuel pressure to make it easier for the computer to adjust for it's target afr and hook up the rising rate to add fuel pressure when in boost. Have I lost you yet?
Next on the list...now that you have all this fuel, you have to be able to control it. You do this with your mapclamp, safc, or dtec. Essentially what these do is alter the amount of boost the computer sees to give you less fuel at a given rpm point. For example with a mapclamp, you're clamping a certain voltage based on map signals. The pcm will start to drop timing in order to prevent damage to your engine if it sees more than it's max boost level. On S0 and S1 cars this happens to be just a tad over 18psi. On S2/S3 computers I believe it is upped to 24psi. By using a mapclamp, you can fool the computer into thinking you're only running 14psi as an example (you can select any psi you want based on your voltage). If the computer is only seeing 14psi and you're running 20psi, the computer will only give you enough fuel to safely opperate on 14psi. Since you're running more boost than 14psi you will have less fuel than what's recommended and it will lean you out. This is a good thing because you can make more power this way, but you have to be careful not to lean out too much.
Safcs work the same way, only instead of being only 1 clamp, you now have 12 clamps and they're user adjustable. You can place them anywhere you want in the rpm range and set them at any voltage you want based on percentages instead of volts. As an example, you can pull out 20% fuel instead of having to run say 4.37v and you don't have to do the math to figure it out. However, there is a chart floating around somewhere that tells you what voltage correlates with what boost level so you don't get too confused with it. You may also choose what rpm points you want to use as well like I stated above. This means you can spread out your rpm points and take away fuel based on how lean or rich you are running throughout the powerband. A mapclamp can only pull one amount away across the whole rpm range, an safc can pull several different amounts away at any rpm range. Hope this clears some things up for you.
To answer a few of your questions directly, you can use either S1 injectors and a returnline to make 300whp, or you can use S2 injectors without the returnline. Both combinations will provide enough fuel for that amount of power. Your stock fuel pump can only supply so much volume and it doesn't last long when it's being overworked. A larger fuel pump will supply more volume, not more pressure. You'll still be working off of your stock 58psi or you can raise/lower the pressure via a returnline. It is NEVER too early to add a fuel pump as it is cheap insurance incase you start reaching the limits of the stock fuel system.
A bottleneck fix is something that is commonly done when using a returnline. Essentially this completely removes the stock fuel pressure regulator out of the loop that's set for 58psi from the factory. It also gets rid of the garbage that DCX was nice enough to supply us with that's simply not large enough to flow the amount of fuel needed to make high horsepower. The stock fuel pressure regulator necks down pretty small and we simply can't move enough fuel through it. By going with the bottleneck fix we eliminate this problem and we are able to provide more fuel to the injectors safely.
