951 4" LINDSEY STEEL EXHAUST
Lindsey Racing Full Race / Street Monster 4 inch exhaust for the 951. Do you need a 4" exhaust? Well, that depends. We think you likely do if maximum HP is your goal. On a 2.5L with a long list of mods, but not the biggest and best of everything, we observed a large decrease in exhaust pressure measured between the turbo and cylinder head. With our 3" system and Edlebrodk RPM muffler, the car produced 30 psi of exhaust back pressure at 20 psi of boost in 3rd and 4th gears clear to redline. When we installed the 4" DT system with Flowmaster Race muffler, that exhaust pressure dropped to 25 psi at the same boost level. That's a 5psi drop which is huge! We expect to see a greater drop when we run without a muffler and dump the wastegate to atmosphere for you serious racers. 
What's important to note though is this. By printing both pulls on the same dyno chart, you can see for yourself that by 4000 RPM, the engine was making 75 more Ft. Lbs of torque at the wheels. It makes more torque all the way up the graph. Also note that the engine reached it's peak torque 350 RPM sooner on the graph. Take note that the BLUE pull was started 150 RPM "later" than the RED pull. The numbers are even more impressive if you take that into consideration. That would become 100 Ft. Lbs more torque at 4,000 RPM and peak torque 500 RPM sooner. Either way you slice it, the numbers are a HUGE difference. Even on a modest engine and boost like this one. This engine has a stock head and intake. With head and intake upgrades, and/or a larger turbo, the results would be even more impressive with the greater need to exhaust what's pumped in. The 4" exhaust will give you more HP and Torque and give it to you sooner. We feel the exhaust pressure needs to be less than the boost pressure. You only need as much exhaust pressure and volume needed to give you the required boost. Anything else is hurting you. One contact of ours runs a record holding drag racer. They run 45 psi of boost with 8 psi of exhaust pressure. When you have higher exhaust pressure than boost, the flow or air actually travels backwards through your engine when valves are in overlap. It's called reversion. The more the exhaust pressure exceeds the boost, the worse the reversion can be. All systems come complete with copper gasket and band clamps. Nothing else is needed for installation. LR-951-EXH-41:
This 3"-3.5"-4" versions is identical to the EXH-42 only we "do not" tie the wastegate outlet back into the primary system. We supply a small slash cut 45 degree dump pipe for the wastegate outlet. This is not recommend for a street driven application. It's simply an option for the dedicated track car wanting to save a little weight, cost and perhaps gain a few HP. LR-951-EXH-42:
Same as the EXH-41, only we "do" tie the wastegate outlet back into the primary tube. We recommend this arrangement for a street and street/track car. OPTIONAL 3" TURBO DOWN PIPE:If you have been considering topping off your exhaust system purchase by adding our 3" Turbo Down Pipe, this is the perfect time. When you select the Turbo Down Pipe option now, we substitute the normal 3 bolt triangular flange wastegate pipe inlet connection for the V-band connection that our Down Pipe uses.
THERMAL COATING:If you wish to have the exhaust thermal barrier coated, select either the EXH41 or EXH42 with thermal coating. That adds $150 to the price of a system. Highly recommended for a track car. It will help keep the heat from entering the driver compartment. The thermal coating also aids in keeping up the velocity of the exiting exhaust by helping maintain the heat in the pipe rather than letting it cool down as quickly and slow down. It will also add to the life expectancy of the exhaust. With or without the thermal coating, the exhaust will give you many years of use. MUFFLERS & MRPs:The systems do not come standard with a muffler. It's an option you purchase separately. Some of you may already have a muffler you want to use so we don't force you to purchase one. The dimensions of the mufflers we use are 19" overall length, 4" center in, and 4" center out.
OPTIONAL CAT:All exhausts have a cat replacement pipe included with them. It's the second pipe in the system. You can remove that pipe and add our performance CAT at any time or select it with you exhaust purchase.
TIPS:The standard 4" exhaust comes with an outlet pipe from the muffler which serves as the exhaust tip. It's either plain finish or ceramic coated depending on what option you select. These "optional" tips slip over that 4" outlet and dress it up with polished Stainless Steel if you would like something with a little more bling. Just remember they are not required since the exhaust already has an outlet/tip.
PRE-MUFFLER MUFFLER:The 4" system sounds awesome with any of our muffler choices. For some however, it may be a little to loud. For them, we offer a pre-muffler muffler. This is a blow through muffler with little or no restriction that goes in place of the second pipe in our system. The piece is manufactured by Flowmaster and is called the "Outlaw" muffler. The Outlaw was specifically designed for racing. The round case allows for installation in limited space applications. The design incorporates sound attenuation rings without the need for packing materials.
02 SENSOR BUNG & PLUG INSTALLED:If you plan on using a Wide Band Oxygen Sensor, we can WELD the bung on the exhaust pipe for you before shipping your system. The additional charge is for the Bung & Plug Kit and labor to install WELD the bung. You can select this option when ordering your exhaust. (Optional) WASTEGATE OUTLET DUMP TO ATMOSPHERE MUFFLER:Any of our 944 Turbo exhausts have the option to dump the wastegate to atmosphere. When you select that choice for your system, you get a Wastegate Outlet Dump Pipe or turn down as standard equipment supplied with the exhaust kit. The sound coming out of that can be loud since it's pre-turbo. So we developed a Wastegate Outlet Muffler. You can select this optional Wastegate Muffler through the exhaust checkout process. We will supply this outlet muffler, and you will not get the standard turn down. 
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