Like others have added.... They lost low end torque with the IPD compettion goodies (82MM), me being one of them. Works well in upper rev's, but not down low.


Did you add your mods all together, or all at once? I have the same as you less the headers, and dis all mine one at a time.


I have softronic tune.

Any comments on the above anybody??

 

My car has more low end than it ever did. Its a DD and because of countless hours of seat time i can feel even the smallest change. I have a much stronger and easier pull at low RPM, Mid RPMs are way better than stock and High RPM are a touch better.
There is absolutely no reason for you to lose low end when getting a bigger TB. You are providing the engine with more air. If it can’t use it, it can’t use it. There is no reason for it to be losing power at low RPM as long as your 2 stage intake works as it should.
People tend to lose low end when they open up exhaust. At low RPM the gas has free-er flow with aftermarket exhaust, it has room to expand and cools and because of that it flows slower thus starts rubbing the engine of power. At high RPM there is more exhaust generated by the engine and that volume is able to move more efficiently through your new pipes and you gain power there. I can attest to it when i got cross-over Cat-bypass pipes. I had no go below 3K. When i added 200 Cell cats, i got most of the low RPM power back. Because now with catalytics in the way exhaust wasn't expanding as much, kept a touch under pressure and kept flowing nicely (this is what everyone likes to refer to as back pressure but they have no idea what it is and why it helps).
When i added 82MM TB my engine now had more air going in, that air translates to more exhaust flowing at all RPMs and thus filling the available space and utilizing the flow of the new exhaust better and bringing back my low end.

Another thing contributing to mass low end loss is the X style exhaust (my opinion). Theoretically you’d think it helps by scavenging but just take a look at that cross section, it’s a huge opening for exhaust to expand in to. Such open space is bad for flow. Exhaust slows down when it expands that much.


All changes to my car were made in steps. ECU, BMC air filter, 200 Cell cats, 82mm TB/ Softronic Plenum (Not IPD), headers. Two single most felt changes were on ECU and headers. Minimal on changes in power were felt on TB and 200 cell. However headers completed the package nicely. It certainly was last restrictive part of it all. Basic principle; more air in, more exhaust out.
After all of it was done, last thing i did was to change the stock flex pipe between airbox and TB to a a 3.25inch smooth elbow.


Power starts kicking in on my car a touch under 2K RPM. Stock it was around 3K. And its more linear vs almost a Turbo spool up effect.
I can cruise in 6th gear at ~1800 RPM and not have to downshift if I want to pick up speed.

 

Okay confirmed. Had a dry few hours through the day. Took the 997.1 4S out and the X51 headers hands down have to be one of the best sounding and feeling mods I've done to date. Great sound and subtle power shift. I should have done this 9 months ago LOL.