HKS centerpipe installed, tuning needed?

[jjrally85]

So I installed the HKS centerpipe on my RA, and my idle has dropped to about 1000rpm's. Additionally, in every gear my rpms are consistently 500rpm's lower than they were with the stock pipe at the same speeds. I understand there is a bit more airflow out the back end with this pipe, but do I need to compensate with any minor tuning? I have gained about 5-8mpg in stop and go traffic due to the more efficient operation, but i don't want to do any damage to the engine or ecu.

[MikeW-RRE]

?

Is this your only mod? 'Splain better what parts were on before this center pipe change.

You say the idle is "down" to 1000? What was it before? :-P

Mike W

[Blaze]

every gear my rpms are consistently 500rpm's lower than they were

I'm having trouble understanding how a pipe changed your gear ratio.

+1 for more information.

[jjrally85]

Ok the car was bone stock otherwise when I installed the pipe. My thought pattern is that since there is more exhaust flow, and thus a slight reduction in back pressure, that the engine is running a bit more efficiently than before.
Is this completely wrong? Maybe I am just imagining the drop in rpm's during normal driving, but my idle does seem to have dropped to just under 1000rpm's.

[TheBlackBeast]

Isn't idle supposed to be a little less than 1k?

If you didn't swap out the stock exhaust, you still have a major bottle neck and wasted a bunch of good money on a center pipe...

The stock exhaust has a baffle inside it with a spring loaded trap door. It won't open until there is enough pressure in the exhaust to open it. So most of the time, only one exhaust tip is funneling spent exhaust fumes, until you really get on it. By the time you do get there, the turbo has worked so hard you negate anything the center pipe might do for you, other than to allow you to put more pollution into the air. :rolleyes:

[jjrally85]

Well this is why I'm here! I guess I fell victim to a little marketing there, 'increase your low end torque while maintaining high-end power!' Well at least I got the bottleneck idea, I only installed this pipe with the intention of later upgrading to an aftermarket axel-back system that would [I]actually[I] yield some better flow for me. I also intended to go for a more aggressive tune through AMS, and add an intake for good measure (which seems like a waste after reading some of the posts on here) but I don't want to violate my warranty. Which pretty much leaves me with exhaust upgrades.

Like I said, I need some input which is why i'm here. This is my first car, and I've been driving a 97 vw jetta for 8 years so I never had the opportunity to tinker and upgrade :D

[jjrally85]

I double-checked this morning and my idle is at 500rpm's