Hogan Downpipe

Just a heads up, the 3 inch hogan downpipe made for 97+ bonnevilles is compatible with all 97+ rivieras, it's a 4 bolt flange, so if you're like me and don't have access to welding talent, it's true bolt on. I emailed them about it, and just got a response back today.


http://hoganperformance.com/DP8S.htm

Great find! Are you going to buy one? That's a really promising mod according to that dyno sheet.

yeah, I wanna go with that one, but i'm still debating if it's worth it to spend the cash on a dp, or just save it for headers

Here's my feelings on our exhaust: for the money and install time, a 3" down pipe is a much better improvement than headers. You get 10 hp with that down pipe vs. maybe 15 hp with headers. It's 1/6 the cost, and twice as easy to install. Plus, you won't have the noise/harshness that headers have.

Unless you want the absolute most power possible, and you plan on modding quite a bit more, I'd try out the pipe.

yeah, good advice, I wasn't sure how much more hp the headers were pulling.. doesn't seem like too hard of an install

Is it an either/or deal? DP or headers but not both?

Yes, it's either/or. SLP headers come with down-pipe built in, called a flex-pipe. Chances are other header varieties would not mate up with any of the available down pipes.

The built in SLP downpipe isn't as big as the Hogan pipe?

Crikey, if it's a 5 hp difference between headers and the DP, and you can't use both, why not get a DP and, uh, what are they called - togs? The smoothed out manifolds?

With more serious mods, like a cam, rockers, or very small SC pulleys... headers should outflow any downpipe/PEM combo. SLPs are advertised giving "up to 25hp gain" But if you only have a few things done to the engine, they are a bit overkill, imo. They really work when you're trying to flow a lot of air.

From what I've read in other threads the DP's don't fit real well,
something about the gasket doesn't match up right? Is one DP a better fit than another?? I need to get educated about this stuff...

This pipe is fitted for the Bonne. Has anyone tried a Bonnevile DP on a RIv?

One more mod to add to the list... that was supposed to be shrinking. I AM interested in doing a DP, bolt-in would be the way for me to go.

I'm betting a big company like Hogan would have a return policy if it didn't fit? Who's going to be first?

How does that dp manage to fit on 2 different generations of Bonnevilles?

The dyno car wasn't stock...It looks like it has a 3.4" w/supporting mods before the dp so I imagine it would benefit the modded car more than a stock car.

They do say it bolts right up on all 97+ rivieras, so like Aaron said, i'm sure they would take it as a return if for some reason it didn't fit..

RhinoFLA wrote:

They do say it bolts right up on all 97+ rivieras, so like Aaron said, i'm sure they would take it as a return if for some reason it didn't fit..

I would make sure to ask them first before you order. I bet they have a restocking fee or something to go along with it.

I emailed an inquiry, asking if they had test fit these to a Riv. I'll bet not, or they would list the application on their site.

The riv and bonneville have the same DP p/n.

The slp knock offs are only 40$ more than that DP, but you don't have the convenience of being a bolt in.

Curt Hogan replied to me this morning. Looks like I'll give this a try at some point, maybe later this summer.

Quote :

Thank you for the interest. Yes, our DP8S is a direct fit party for the Rivera in 97, 98 and 99 only.This pipe bolts to the factory manifold and to the inlet flange on the catalytic converter. Installation requires A GT1 gasket at the upper connection and a GT3 at the lower. If you are interested in purchasing these items the cost is as follows.
DP8S 139.95 plus 10.00 with optional interlock flex for tick and whistle free operation.
GT1 13.00
GT2 5.00
S&H 17.50 (Lower 48 States)
If you wish to order, please make PayPal payment to Belair427@cox.net
and we will ship within 48 hours.
Thank You
Curt Hogan
Hogan Performance

All systems go...

Why not include '96s?

dunno...

gonna rust up an fall off.... 409 SS an steel flanges....

AA wrote:

All systems go...

Why not include '96s?

b/c the 96's do not have bolt up flanges. ours is welded to the cat and has a different bolt-up at the collector. the zzp DP will work on the 96's but it must be welded in place and the upper gasket is a dounut type not a flat gasket. i have very little leaking with my zzp dp, and i reused the stock gasket even tho it is a little bit small. i also used 3" pipe all the way to the resonator
also the holes on the zzp/aftermarket dp's do not directly line up with the 96 holes so they must be drilled out a little bit.

TType_Riviera wrote:

gonna rust up an fall off.... 409 SS an steel flanges....

You think the steel flange won't hold up for an acceptable length of time? Or is it the 409 SS you're doubting? I'm not familiar with the specs on 409SS, we deal with 304 and 316 where I work.

If read the 409 develops a surface rust, but that is supposed to be a protective coat that prohibits further corrosion. If the 409 is coated, it should last. My headers are 409. If I bought the Hogan DP, I might see about having it Jet coated, if they could do it with the braided section, I don't know.