PLog/downpipe vs. lower-cost headers? (With cat.) Total cost, and ease of installatio

**wmorrison65** · 07-23-2015

Relative to GTP/L67, but I figured it's more of a question for the general section.

From what I understand, the front exhaust manifold is pretty restrictive, but the rear exhaust manifold is not too bad. And the downpipe is a bit restrictive, 2.5" but double-walled so it's less than that internally. Then there's the U-bend.

The only aftermarket alternative I find for the front manifold is the ZZP Power Log, except headers.

A PLog plus a downpipe are already in about the same price range as Speed Daddy headers, right? Am I forgetting any extra parts that one or the other configuration will require?

So if the goal is, a daily driver, with no problems passing emissions (no OBD codes popping up for the cat,) running on no more than 93 octane, just better "breathing," better KR, and whatever few horsies come from it are a bonus, which is better? Is it worth going for a PLog/downpipe, or is it better to just go right to headers? Will either setup be easier to prevent OBD codes for the cat?

**ericspecullaas** · 07-23-2015

go with headers its better for you

**Slick2500** · 07-23-2015

If all you plan on doing is headers you will loose some power, idk if it will be enough to notice on the butt dyno though.

**J57ltr** · 07-23-2015

Wait, lose power with headers? How so?

Jeff

**Fivefingerdeathpunch** · 07-23-2015

I'd go plog and downpipe to keep it simple.

With headers you will have to source a cat converter to get welded in or clamped in.

**sseilmnop** · 07-23-2015

Speed daddy heads are Chinese, there quality can vary. Some love them and some curse the day that they installed the leaky headers that never fit right.

Don't no what you have until your hours in to the install!

**wmorrison65** · 07-23-2015

Originally Posted by ericspecullaas

go with headers its better for you

Thanks, but how about an explanation/justification? (Anybody?)

Originally Posted by Slick2500

If all you plan on doing is headers you will loose some power, idk if it will be enough to notice on the butt dyno though.

Are you basing that on the "engines need backpressure" hypothesis/myth? (Not 100% sure whether it's myth.)

My '01 Audi TT 225hp with a 3" aftermarket downpipe and an APR tune has no noticeable loss of low-end torque compared to when it was stock (but plenty of noticeable top-end power.)

Originally Posted by Fivefingerdeathpunch

With headers you will have to source a cat converter to get welded in or clamped in.

Won't that also be true with an aftermarket downpipe (to go with the PLog?)

For a 3" downpipe, probably for sure. For a 2.5" downpipe, well, since the stock downpipe is actually less than that because it's double-walled, I'm not sure about the stock cat inlet/outlet diameter or flow.

Overall, since the price is similar (unless I'm forgetting some parts, HELP,) I'd think headers would be better to give room for future mods (even if currently unplanned) UNLESS PLog/downpipe make it easier to keep the rear O2 sensor happy (e.g the PCM readings.)

I want to stay completely emissions-legal. All Connecticut cares about is that there are no OBD codes. Not sure if they manually inspect the exhaust. I don't want to delete the rear O2 sensor reading in the PCM or emulate it.

**99GT2dr** · 07-23-2015

I'm happy with my plog/dp combo, hitting 10.5k on the maf with a 3.2, so it's flowing good enough. Would I prefer a set of SD headers? Hell no. Now a set of tog's or zzp's I'd take in a heartbeat, but I'm not willing to shell out that kind of money atm.

**EHB** · 07-23-2015

i'd say i had a total of 1.5 install time for both a plog and DP everything lined up and sealed perfect....never done headers before but i believe you'd be lookin at more of the 4 to 5 hour range. speed daddy's would definitely be cheaper. shipped with both new gaskets i paid 259 for just the 3 inch catted. got the 50 dollar cat coupon for sending my stock cat back and got the plog and 2 crossover bolts for 99 bucks i think it was like 115 with shipping. so about 375 bucks. i'm not planning on going deep with mods so i went with the easy, maybe slightly more costly option and i'm happy with it.
some cars throw a code with the zzp catted DP. some don't. they sell an o2 emulator for like 50 bucks to keep the code at bay. better to put that 50 towards a tuned pcm and have the code removed.

**Scottydoggs** · 07-24-2015

Originally Posted by J57ltr

Wait, lose power with headers? How so?

Jeff

i had 8 psi before headers, after the headers i was at 5.3 psi. headers flow better and will lower your boost. why you want to put a smaller pulley on once you got headers. or just drive it, you dont have to pulley down.

**Slick2500** · 07-24-2015

Originally Posted by wmorrison65

Thanks, but how about an explanation/justification? (Anybody?)

Simple most headers flow better than the plog downpipe combo.
It's kind of like shorty headers vs long tubes. The plog and dp are kinda like shorties and headers are more like long tubes. At least that is how I look at it.
If I ever modded another l67 that wasn't going turbo, I would go with SD headers again.

Sent from A Galaxy Far Far Away

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