vgalewick Report post Posted July 29, 2011 My coach has a Cummins 400 ISL, and I am interested in more power and better mileage....who isn't? There are numerous companies that sell aftermarket "chips" that claim 20-45% more power and 15 to 20% better mileage, for about $700....I spoke with my Cummins service rep, and he was surprisingly positive about it, and told me how his Cummins powered Dodge truck added 200 horsepower with such a "chip".... He also offered to upgrade me to 425 horsepower for only $125, with the Cummins software package. I am very interested in finding the best possible company to buy one of these from, and I am hoping someone has a good experience and could provide a referral to a good company to buy from...here is a link to one of the companies I have looked at: http://illinoisdynocenter.org/ Share this post Link to post Share on other sites
vgalewick Report post Posted August 4, 2011 I am surprised that no one has had any information to add to this thread...has no one tried any of these power adders ? I guess I will volunteer to be the 1st and report how well it seems to work... vgalewick 2009 american allegiance 400 cummins isl Share this post Link to post Share on other sites
larryanelson Report post Posted December 19, 2011 I have a 400ISL in a 38' 2003 country couch with 2 slides and a tag axle, I had the computer set up for better fuel consumption. I have gained 5 to 7 ten of a MPG over the last 30K miles, This includes the Colorado mountains, Alaska, Boston/Washington DC, Texas. After this was completed they tested on the Dyno with 395 HP to the ground. The cost was 1K. I am well pleased with the tune, I can run with 500 HP Cummins and 625 Cat's all pulling a vehicles 4 wheel down. Just for your information I did not really realize the extra fuel consumption and power until I turned over 42,000 miles. Share this post Link to post Share on other sites
skyking650 Report post Posted September 19, 2017 Just added Bully Dog Heavy Duty Tuner to my ISL.....have not made any trips yet but seems stronger. Set on the Economy + Performance setting which is supposedly an ad of 15% power and ups the economy. Will keep you all know once I have more time driving it. Share this post Link to post Share on other sites
five Report post Posted September 19, 2017 Another six year old thread. Share this post Link to post Share on other sites
