I searched... and only found "Rich's Rotary" who had 5 or 6 separate for sale posts recently with a laundry list that included a 3.5" midpipe with a Borla muffler in it. Which eventually sold.

I wouldn't mind having a Borla in the midpipe, but I'm not sure that it would clear my driveshaft, and since I don't have a driveshaft in the car yet, it's sort of difficult to figure out whether or not it would clear.

In that case... anyone know where I can find a 3.5" stainless midpipe with or without a Borla muffler?

 

well could you make 4 inches work? because I know that someone make a 4" out there. I want to say blitz, or maybe JIC. Why don't you just make one? You are doing everything else aren't you? when is the monster going to be done anyhow?

Matt

 

I'm not sure if this helps you or not but I beleive Border Racing makes a HiFlow Cat' in 3.5". You can contact jt-imports or fullytuned7 on the other forum.

If you have to go custom,you can get 3.5" flangese "here"

 

Obviously I can have one made, and I'll have to "neck down" the rear of the pipe to mate with the 3" cat-back anyway, but I'd rather not have to totally reinvent the wheel if I don't have to. Having a pipe pre-made with the right bends to fit the car saves me a lot of hassle. I also don't know of anyone who can mandrel bend 3.5" stainless off the top of my head.

My plan is to use 1 7/8" primary long tube headers cut and modified to "Y" over to the passenger's side to twin 3" collectors. Two 3" collectors then transfer into a single 3.5" midpipe, and then into the 3" cat-back.

The advice I got from the pros was to have as much volume as possible in the exhaust path closer to the engine where exhaust temperatures are higher. As the exhaust cools on its way to the tail pipe, the gas takes up less space, and a 3" cat-back with twin 2.25" or 2.5" (not sure what the RB twin tip is) will be fine. Up towards the engine, the volume needs to be much higher, though.

8 x 1.875" = 22 sq. in. (eight 1 7/8" primary tubes)
2 x 3.0" = 14 sq. in. (two 3" collectors)
1 x 3.5" = 9.6 sq. in. (one 3.5" midpipe)
1 x 3.0" = 7 sq. in. (one 3" cat-back)

I also plan to run an electric cut-out to dump exhaust straight to atmosphere for maximum performance at some point before the midpipe or at least before a muffler placed in the midpipe. I've been thinking about running a Borla in the midpipe to cut down on the noise when not absolutely necessary, and it should have very little effect on performance.

 

Haven't heard of an off-the-shelf 3.5" midpipe but I found these guys as I was looking for parts to fabricate a 3.5" downpipe..

http://www.stainlessworks.net/

They'll mandrel-bend 3.5" 304 stainless (or whatever you want) to your liking for pretty cheap. They also sell 3.5" to 3" transitions. Midpipes are only bent in 2 dimensions.. I'm sure if you send them dimensions, they could probably do it in one pipe..

For what it's worth.

..dave

 

[QUOTE]Originally posted by jimlab
[B]The advice I got from the pros was to have as much volume as possible in the exhaust path closer to the engine where exhaust temperatures are higher. As the exhaust cools on its way to the tail pipe, the gas takes up less space, and a 3" cat-back with twin 2.25" or 2.5" (not sure what the RB twin tip is) will be fine. Up towards the engine, the volume needs to be much higher, though.

Jim, I think the RB twin outlets are considerably smaller than that - 1 7/8 comes to mind. I'll try to measure tonight. I was shocked to see it when I got mine, its quite a reduction in area from the 3" inlet. Maybe they've changed?

 

I haven't measured mine, but the design has changed from the last RB twin tip I had.

 

I may end up grafting different tips onto the muffler anyway. I can't get that damn Racing Beat logo off the tips no matter what I've tried, short of 80-grit sandpaper.

 

See if Chuck @ Rotary Extreme is done making his. 90mm Titanium should match the rest of your car! Rotary Extreme Exhaust

HKS makes a 4" midpipe catback combo, not really what you're looking for.

I would go with custom, just because something as minor as the inlet angle on a pre-made pipe may make it difficult to line up your y-pipe.

 

if you're just gonna hack up the rb muffler, why not just sell the rb and go w/ a full custom exhaust w/ the muffler of your choice. that way you'll have the exhaust just the way you like it and it won't be too much more expensive than piecing everything together.

 

Jim -
Mine (from 1998?) look like yours in the picture from that angle, but about 2 1/2 into the tips, the pipes neck down to 1 7/8 or less (didn't have accurate measuring tool this morning), and that diameter appears to carry through the can.
For those who don't want to do the math, a 3" ID inlet would be 7.0686 sq in, while 2 - 1 7/8" ID outlets would be 5.5223 sq in, only 78% percent of the inlet area, and a whole lot smaller than the 22 sq inches in the headers.