SixStrings12 1 Posted January 26, 2022 So, after the insides of my stock exhaust on 2002 foreman 450s let go and started rattling, I purchased an MPRB slip on after market exhaust and installed it a few weeks ago... Let's just forget about the "slip-on" bit - I had to take it to an exhaust shop and get the inlet enlarged by 0.05 of an inch to get it to "slip-on" to header pipe.. Then the mounting instructions were completely wrong...said to discard the OEM spacers - ahh..no...you either use the spacers or have to invert the mounting tabs to get it to clear the shock... Then it had an air leak at the exhaust to inlet pipe connection - all they tell you to do is slip the pieces together and use a supplied spring to keep the exhaust and inlet pipe together...ahh, again, no...you need to buy some Exhaust goop and ensure that connection is air tight. So, after all that nonsense, I take it out for a test ride... Bottom end power is fine...actually feels like a little more grunt..but I lost at least 10 km/h on my top end...I could hit 60 km/h no problem with the stock exhaust, now I am lucky to hit 49 km/h. FYI, I do have 26" zillas on this thing, so I know that saps some top speed from stocker tires, but still... You can hear the motor winding out, but it simply does not get back up to top speed any longer... Before I check the spark plug, anyone else experience something like this with an aftermarket exhaust? Yes, I will eventually cut open the stocker and repair it, but wanted to get this thing going asap and bought the MBRP exhaust... Thanks for any insight. Share this post Link to post Share on other sites
jeepwm69 7,751 Posted January 26, 2022 So did it do 60 KM/H with the 26's on it, with the only difference at all in 60 KM/H and 50 KM/H being the changed exhaust? 1 Share this post Link to post Share on other sites
SixStrings12 1 Posted January 26, 2022 (edited) So did it do 60 KM/H with the 26's on it, with the only difference at all in 60 KM/H and 50 KM/H being the changed exhaust? Yes, only change was the exhaust. Thanks Edited January 26, 2022 by SixStrings12 1 Share this post Link to post Share on other sites
jeepwm69 7,751 Posted January 26, 2022 Sounds like either the new exhaust doesn't have as much flow as stock, or it might have more flow which means your jetting is now off. Have a link to the muffler you put on? Share this post Link to post Share on other sites
SixStrings12 1 Posted January 26, 2022 Yep...this is the exhaust: https://mbrpexhauststore.com/slip-on-system-w-sport-muffler-honda-trx-450-foreman-1998-2004-400fw-1995-2003/ Share this post Link to post Share on other sites
Fishfiles 20,147 Posted January 26, 2022 Is this what you installed ?? Would think it is more restrictive to the flow since you lost --- Honda made a 450 Sport ATV , maybe this muffler is for it , since you mention it was suppose to use a spring to hold the muffler on , like a Sport ATV does ---- maybe your old muffler was worn out giving you more performance , LOL $194.99 BRMP Honda ATV Direct Replacement Slip-On with Utility Muffler #7105 Share this post Link to post Share on other sites
jeepwm69 7,751 Posted January 26, 2022 Given the only review on there says it bolted right on and was a perfect fit, and it says "improved flow" and "no tuning required" Given what all you had to do, I wonder if you didn't get the wrong part....... Share this post Link to post Share on other sites
SixStrings12 1 Posted January 26, 2022 2 hours ago, Fishfiles said: Is this what you installed ?? Would think it is more restrictive to the flow since you lost --- Honda made a 450 Sport ATV , maybe this muffler is for it , since you mention it was suppose to use a spring to hold the muffler on , like a Sport ATV does ---- maybe your old muffler was worn out giving you more performance , LOL $194.99 BRMP Honda ATV Direct Replacement Slip-On with Utility Muffler #7105 Yes, this thought crossed my mind as well... So, obvious next step is to do a plug chop, but I have asked this before on other forums and just got 'crickets'... How do you do a plug chop on a semi-auto transmission ATV? You are supposed to go balls out in 5th gear and cut the engine, then inspect the plug - how do you do that on a semi-auto machine and not destroy it? Thanks for the replies everyone - much better site than "the other one"... Share this post Link to post Share on other sites
Fishfiles 20,147 Posted January 26, 2022 So what you calling the other site ? HondaAtv ?? I have a 2002 450 with a stock muffler , boy , that muffler is expensive if you were to ever have to buy one , they were over $1,100 without the heat shield , that muffler is no longer available from Honda , but I do see one looks exactly like stock for around $300 on e-bay , probaly Caltric --- also have a 2000 with a HMF muffler , that one screams and is very loud , but will only do 19mph with a 20 mph wind at my back , LOL , it has 34.5% gear reduction with 29.5s Share this post Link to post Share on other sites
Fishfiles 20,147 Posted January 27, 2022 New 1998-2004 Honda TRX450 Foreman ATV Exhaust Pipe Muffler $299 free shipping https://www.ebay.com/itm/273269756651?_trkparms=amclksrc%3DITM%26aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160811114145%26meid%3D9b1f627cfdc045a5b5de705b5a0405c0%26pid%3D100667%26rk%3D3%26rkt%3D8%26sd%3D351821951244%26itm%3D273269756651%26pmt%3D0%26noa%3D1%26pg%3D2334524%26brand%3DHonda&_trksid=p2334524.c100667.m2042 1 Share this post Link to post Share on other sites
jeepwm69 7,751 Posted January 27, 2022 18 hours ago, SixStrings12 said: Yes, this thought crossed my mind as well... So, obvious next step is to do a plug chop, but I have asked this before on other forums and just got 'crickets'... How do you do a plug chop on a semi-auto transmission ATV? You are supposed to go balls out in 5th gear and cut the engine, then inspect the plug - how do you do that on a semi-auto machine and not destroy it? Thanks for the replies everyone - much better site than "the other one"... I think the next step for me would be to call the muffler seller and confirm that you got the right part. Of course, now that you've "tweaked" it they might not be willing to do anything, but won't hurt to call them and confirm that you got the right part. Share this post Link to post Share on other sites
1 arm chic 9 Posted June 10, 2022 On 1/27/2022 at 4:04 AM, Fishfiles said: New 1998-2004 Honda TRX450 Foreman ATV Exhaust Pipe Muffler $299 free shipping https://www.ebay.com/itm/273269756651?_trkparms=amclksrc%3DITM%26aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160811114145%26meid%3D9b1f627cfdc045a5b5de705b5a0405c0%26pid%3D100667%26rk%3D3%26rkt%3D8%26sd%3D351821951244%26itm%3D273269756651%26pmt%3D0%26noa%3D1%26pg%3D2334524%26brand%3DHonda&_trksid=p2334524.c100667.m2042 I like the price from January better then in June lol it’s $349 now I’ve been needing a new 1 desperately but I never knew which 1 to get. Is this 1 quiet? I don’t want a real loud 1 that’s what’s actually kept me from buying 1 Share this post Link to post Share on other sites
Fishfiles 20,147 Posted June 10, 2022 12 minutes ago, 1 arm chic said: I like the price from January better then in June lol it’s $349 now I’ve been needing a new 1 desperately but I never knew which 1 to get. Is this 1 quiet? I don’t want a real loud 1 that’s what’s actually kept me from buying 1 A OEM TRX450 muffler is ridiculous in price = right at $1.200 without the 3 heat shields and the exhaust pipe I don't have a Armor Tech , I have two 450s , one has stock muffler / pipe , the other is a HMF , it is very loud , too loud to tell the truth, that Armor Tech pictured above looks like stock , I think it would be close to stock sound ---- Caltric is another cheaper than OEM brand close to stock , I have one of those on a 300 , it has lasted for a long time 1 Share this post Link to post Share on other sites
