I have a rusted flex pipe, and I was thinking about having they shop change out everything back from the A pipe.

I have a stock 95 Vtec Prelude. I don't want a loud sound, but I would go for a deep sound and some better power, or mileage.

I considered either having a new flex welded, or buying a cheapo ebay header, but I think that the CAT is pretty restrictive. So I figured that if I changed the CAT then I should just change it all to 2.5"

What should I do?

thanks

 

I'm not sure a 2.5" downpipe would be a good combination with the ultra small primaries of the stock header.

 

Should I run a 2.5" exhaust at all?

 

im running a megan header with the 2.5'' collecter mod and full 2.5'' exhaust i like it alot but last time i went to the dyno i was automatic

 

With the stock header and 2.5" collector, will it hurt performance?

I like to motor around 3-5k, only into Vtec occasionaly.

Should I just get the cat and flexpipe changed? Should I change the cat back to 2.5"?

What about 2.25"?

Anyone used the stock header w/ a larger collector?

I thought that the stock Vtec header was good for a stock car.

thanks
matt

 

If you're going to run a stock header (or don't want to spend a lot) don't bother investing in a DC or something of the like. I'd say just extrude hone out the stock one and you'll get about the same gains as you would w/ a DC. Cost a little bit less and don't have to worry about it cracking.

 

Has this been covered before? I have searched the archives, but didn't really find a good definite answer as to what is the best way to gains w/ a stock motor, and no $500 to drop on a header. I will buy a good header sometime, but I need to fix this now.

thanks
matt

 

Should I go to the Engine Forum?

 

If you're not running an exhaust the catalyctic converter is the absolute least of your restriction issues. It'll outflow everything else in your system unless it's on it's way out, it's as simple as that. There is just no point to consider what you're doing unless you open up the SYSTEM instead of the one component. Does the straw flow better if you put a bigger straw at the end? No, it doesn't. Same principle works here. There just isn't any reason to waste the money doing that if you're not going to open up the system completely. Get it repaired to your satisfaction and invest in something good down the road.

 

Ok there is a mix up here. The first line of the thread says I am going to open it up from the A pipe back. So yes I want to do the whole system. The only thing stock is the modified stock header.

I want to go to 2.25" or 2.5" from the Apipe back.

Cheap headers are an option. I just figured that the minimal gains on a cheap header arn't worth it.

 

Small primaries again... you still aren't opening everything up. As I said before, if you want a cheap fix extrude hone your header. It'll be better than a DC but you won't get 2.5" out of it. I'd just patch/replace the flex pipe and be done with it for now. Get a custom exhaust w/ dual resonators down the road when you can afford a header/exhaust. Using a stock manifold for anything other than absolute need is a waste... Just as an FYI ALL off the shelf exhaust systems (short of the T1R) are 2.0" or smaller off the cat.

 

Yeah, there is a local place that will do all the exhaust including parts at whatever dia. for $400. I figure get a good cat and keep as close to stock as I can on the resonators and muffler.

Would I notice bad performance if I changed to 2.25" now on everything but the header? I realise this is far from ideal.

Thanks
matt

 

Here is what everyone is saying. Dont spend money until you can afford to upgrade/free-up everything. TimeRacer has been telling you that several times over now!

 

I think the key here is this:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by M@ &raquo;</TD></TR><TR><TD CLASS="quote">I like to motor around 3-5k, only into Vtec occasionaly.</TD></TR></TABLE>

Don't do anything to it. If you make any part of the exhaust system larger diameter, it will improve performance at the high end and make the low end *worse*. Because you're staying at 3-5k, what you have is probably perfect. Leave it alone.

And you also said:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by M@ &raquo;</TD></TR><TR><TD CLASS="quote">I need to fix this now.</TD></TR></TABLE>

Fix? Nothing is broken.

 

Thanks. I was thinking that larger dia might do that.

I have a leaky flex pipe.

So, yeah I know what to do then, sorry for the confusion.