Ever since I put the testpipe on, my low end went to a complete nose dive. Then again, that's expected. If I accelerate (not entering boost) it takes freakin' forever to get up and go. On a positive note, once it passes 0 psi, that thing just rips to 5 psi. Oh well, can't really complain about the trade-off though. Maybe an UDP will help.

will a highflow cat have more low end then a test pipe? I would think it would.

yes a highflow will add low end and decrease top end. specially on turbo.

yeah i know man the only time you would lose low end if the exhuast diameter is increased to a point where the back presure is "gone"
when you add a test pipe you are increasing exhaust flow.
later
"Z"

It's all good though, at least the turbo spool up is much faster now. Plus, I can actually hit 5 psi consistently regardless of temp. outside. Also, EGT's were affected dramatically, like I run about 500 degrees cooler. The difference is also much noticable at night. So I say it's a good trade-off. Bad thing is that it stinks though, I sure hope they won't have that emissions back here in FL.

Correct me if I'm wrong, but isn't the basic concept of a good exhaust system to get the air flowing in one continuous direction. And with a larger pipe size, the exhaust gases can circulate within the pipe at idle (unless there is greater air force caused by turbo, etc.) causing loss in backpressure. Therefore, during acceleration from a stop the gasses being pushed out have to work against the gasses that were circulating during idle which will result in a loss of low end torque.

That's always what I thought caused it, and someone tell me differently if I'm wrong.

Jay | Black '98 GS

Kris, I didn't notice a lightweight pulley on your mod list. I had my testpipe for about a week before I put on my AFX underdrive pulley. It felt like the pulley made up for most of the low end loss I got from the pipe. You may want to give it a try.

Jay, I always thought about the backpressure caused the piston to travel faster downward on the intake stroke because of the higher initial pressure in the cylander. Maybe someone else could correct both of us. :D


95 Eclipse RS : 5 speed
Gude cams : test pipe : AFX UDP : ram air : Thrush glasspack : Dual air horns : Kenwood KDC 5000 : AutoCommand remote start
incomming - lower strut bars

Yeah, I'm debating whether to get bigger 30lb. injectors or the UDP. I'm moving to an apartment this coming Sept., so money is real tight right now.

Injectors are a must for turboed cars. I would get them first. Who cares about low end when you have boost ;) .

Kris, I don't know what else to tell you except that the UDP should help with the low-end and the injectors won't. Aren't you running 4 pounds? Do you need bigger injecters with that? Maybe after you get that sidemount on, right?


95 Eclipse RS : 5 speed
Gude cams : test pipe : AFX UDP : ram air : Thrush glasspack : Dual air horns : Kenwood KDC 5000 : AutoCommand remote start
incomming - lower strut bars

Yeah, about the 310cc injectors, when I'm able to run 13-15 psi, I was a bit worried that I might max out those 30 lbs. I see most, if not, all you Stage 3 guys have 440's. I'm not sure how to calculate injector sizing per pound of boost. I just don't wanna get the 310's when in the future, I need the 440's to run 15 plus psi.

Oh yeah MetalJim, with the testpipe on, I can actually run 5 psi consistently now ;)